Why did the Prophet (ﷺ) marry Aisha (رضي الله عنها) when she was so young? First things first, we know that she had reached puberty when she married the Prophet (ﷺ). Below are some of the narrations that discuss this matter:
لَمْ أَعْقِلْ أَبَوَىَّ إِلاَّ وَهُمَا يَدِينَانِ الدِّينَ
I had seen my parents following Islam since I attained the age of puberty. [Sahih al-Bukhari, Book 8, Hadith 124]
فَقَدِمْنَا الْمَدِينَةَ فَنَزَلْنَا فِي بَنِي الْحَارِثِ بْنِ خَزْرَجٍ، فَوُعِكْتُ فَتَمَرَّقَ شَعَرِي فَوَفَى جُمَيْمَةً، فَأَتَتْنِي أُمِّي أُمُّ رُومَانَ وَإِنِّي لَفِي أُرْجُوحَةٍ وَمَعِي صَوَاحِبُ لِي
We went to Medina and stayed at the home of Bani-al-Harith bin Khazraj. Then I got ill and my hair fell down. Later on my hair grew (again) and my mother, Um Ruman, came to me while I was playing in a swing with some of my girl-friends. [Sahih al-Bukhari, Book 63, Hadith 120]
We learn that Aisha (رضي الله عنها) had physically matured when she married the Prophet (ﷺ).
The Prophet (ﷺ) was a chaste man and the best man. Much has been written about this from Muslims as well as neutral sources – read more here. All his wives except Aisha (رضي الله عنها) were either widows or divorcees and so the allegations of lust levelled against him by biased haters do not stand. He even turned down lustful offers when the tribe of Quresh sent them as follows:
فاختر أي نساء قريش ونزوجك عشرا وإن كان إنما بك الحاجة لك حتى تكون أغنى قريش رجلا واحدا
If you choose any woman from the Quresh, we will marry you to 10 and if you have any other need, we will satisfy it until you are the richest man from Quresh.
The full conversation between the Qureshi representative and the Prophet (ﷺ) is somewhat lengthy where they even offered to make him (ﷺ) their king if he only let go of his mission of Islam or modified it to their liking; however, only the relevant passage is quoted to prove that the Prophet (ﷺ) was not lustful man. He turned down the offer to marry 10 of the most beautiful women of his choice. The allegations of lust levelled against him by biased haters do not stand.
The reality behind the ages
What is important to remember is that when these narrations are discussed, they are done in the environment when the calendar had been devised. In pre-Islamic times and the times of the Prophet (ﷺ), the calendar had not been formed and people remembered occasions based on major events. For example, the people remembered that the Prophet (ﷺ) was born 50 days before the event of the elephant i.e. when Abraha, governor of Yemen, attacked the Ka’aba and brought some elephants with him. The Arabs knew the months of the year but were generally unconcerned with the years.
In AD 638 (17 AH), Abu Musa Ash’ari (رضي الله عنه), one of the officials of the Caliph Umar (رضي الله عنه) in Basrah, complained about the absence of any years on the correspondence he received from Umar (رضي الله عنه), making it difficult for him to determine which instructions were most recent. This report convinced Umar (رضي الله عنه) of the need to introduce an era for Muslims. After debating the issue with his counsellors, he decided that the first year should include the date of the Prophet (ﷺ)’s arrival at Medina. Uthman b. Affan (رضي الله عنه) then suggested that the months begin with Muharram… The years of the Islamic calendar thus began with the month of Muharram in the year of the Prophet (ﷺ)’s arrival at the city of Madina. Because of the Hijra, the calendar was named the Hijra calendar.
In this context, it is natural that people pay little heed to ages. They took people to be what they appeared to be (see next section below for further details).
When Aisha (رضي الله عنها) narrates her age, she does so later on and by calculating it backwards while it is highly probable that she may not know her age with certainty at the time of her marriage.
The age of the Prophet (ﷺ):
Although the Prophet (ﷺ) was 53 years old when he married Aisha (رضي الله عنها), he looked very young.
عَنْ حُمَيْدٍ، قَالَ سُئِلَ أَنَسُ بْنُ مَالِكٍ أَخَضَبَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ قَالَ إِنَّهُ لَمْ يَرَ مِنَ الشَّيْبِ إِلاَّ نَحْوَ سَبْعَةَ عَشَرَ أَوْ عِشْرِينَ شَعَرَةً فِي مُقَدَّمِ لِحْيَتِهِ
It was narrated that Humaid said: “Anas bin Malik was asked: ‘Did the Messenger of Allah (ﷺ) dye his hair?’ He said: ‘He did not have any white hair apart from approximately seventeen or twenty hairs at the front of his beard.’” [Sunan Ibn Majah, Vol. 4, Book 32, Hadith 3629]
This is narrated by Anas b. Malik (رضي الله عنه) who was one of the last companions of the Prophet (ﷺ) to pass away and when he narrates it, he does so much after the passing away of the Prophet (ﷺ). Therefore, he describes the late description of the Prophet (ﷺ) who passed away at the age of 63. Imagine he had few white hairs at the age of 63, how much would he have 10 or 13 years before that? Barely noticeable, if at all! Not just were his hairs naturally black, his skin, physique, and structure were also young. The following narration is from when the Prophet (ﷺ) was around the age of 50:
قال محمد بن إسحاق: وحدثني محمد بن مسلم بن شهاب الزهري، أنه أتى بني عامر بن صعصعة، فدعاهم إلى الله، وعرض عليهم نفسه، فقال رجل منهم، يقال له بيحرة بن فراس: والله لو أني أخذت هذا الفتى من قريش لأكلت به العرب
Muhammad b. Ishaq said Muhammad b. Muslim b. Shihab al-Zuhri narrated to me: He (i.e. the Prophet (ﷺ)) went to the Banu ‘Amr b. Sa’sa‘ah, and called them to Allah and offered himself to them. One of them called Bayharah b. Firas said, “By God, if I could take this boy/young man from Quraysh I could conquer all the Arabs with him.” [Tarikh al-Tabari also in Sirat Ibn Hisham]
What we learn from this is that people saw each other as they appeared. Bayharah b. Firas called the Prophet (ﷺ) a boy. Imagine how young he would have looked! It would not be a surprise if he, at age 50, actually looked like a 25 or a 30 year old man. When the Prophet (ﷺ) migrated to Madina, at the age of 53, he stopped by with his close friend and companion Abu Bakr (رضي الله عنه) at the place of an old woman, Umm Ma`bad. The books of Hadith and Sirah (biography of the Prophet (ﷺ)) record how she described the Prophet (ﷺ) later to her husband when he came home (i.e. their tent):
I saw a man who is clearly handsome and with a beautiful face. He is well-built. He is neither blemished by a big stomach nor did he have an unusually small head. The pupils of his eyes are very dark, the edges of his eyelids are long and the area around the pupils of his eyes is so white. His eyebrows are perfectly close. He has a very dark hair, a rather long neck and a thick beard. When he kept silent he is always contemplative and when he speaks eminence and splendour show in his words. His words are like sliding stringed pearls. He is a gifted speaker whose words are neither too few nor too much. He has the clearest words and the most audible voice when he speaks. When you look at him from afar, he is the most handsome of all people, and when you move closer to him he is the most pleasant of them. You will never be tired of looking at him. He is like a branch between two branches. He is the most handsome of the three (she means: the Prophet (ﷺ) Abu Bakr and Amir ibn Fuhayrah) and the most important of them. He has Companions who honour him. When he speaks they listen to his words and when he commands they hasten to carry out his order. They serve him and rally around him. He does not frown or nag. [Source]
This description further shows that even at the age of 53, the Prophet (ﷺ) looked very young, fresh, attractive, charming, and charismatic, and as stated earlier, it would not be a surprise if he, at age 50 or 53, actually looked like a 25 or a 30 year old man.
The age of Aisha (رضي الله عنها):
Although nine, she looked much older and this is not a rare occurrence. The passage below is interesting:
The memoirs of one of the ulama who worked in Syria’s family law courts in the mid-twentieth century depicts the troubled process of coming to terms with a modern, Western-shaped law while maintaining a commitment to the canon of the Qur’an and Sunna. It was acceptable, wrote Ali Tantawi, for the ruler or state to introduce administrative laws and restrictions in the best interests of the people. This was allowed under the Shariah not only within the original, narrow window of public interest (Maslaha) but also because God orders Muslims to obey ‘those in authority among you.’ He was thus content to preside over marriage after marriage in his Damascus courtroom while observing the age requirement of eighteen.
What Tantawi could not abide was to endow this law with any moral or religious weight. At best it was a sensible policy for promoting health and welfare; at worst, bureaucratic red tape to be grudgingly endured. Underage couples who married with a private Shariah contract undocumented by the state were still married in the eyes of God. Tantawi also frequently granted exceptions for brides as young as thirteen, as the new law allowed. He recalled how often he had stood next to such girls and found that they were taller than he was and were fully physically mature. ‘So it’s not simply a matter of age,’ he wrote, ‘as those who hastily and mistakenly speak without knowledge or understanding about the marriage of the Messenger of God, may God’s peace and blessings be upon him, the best of mankind, the fairest and most just, about his marriage to Aisha when she was nine years old.’ Had those outraged by this act actually seen Aisha? She could well have been like the girls who came before him in court, especially, he wrote, since girls in hot climes can become mature as young as nine or ten. [Misquoting Muhammad pg. 155-156]
When Aisha (رضي الله عنها) was nine, she may have been much taller than her age and may have even looked like a 15 or 16 year old. This is observable even in our times and you may have seen nine year old girls above 5 ft. (1.52 m) who only grow a couple of inches in the next three or four years. If Aisha (رضي الله عنها)’s case was an exception, she may have been taller than 5ft 2 in. (1.57 m) and grown taller later on and even looked older than her real age. Remember, people did not judge ages based on calendars and birth certificates, they looked at the person and considered them what they found them to be.
What we learn is that during old times and especially in Arabia, people did not look at birth certificates or ages; they relied on how the person looked. If he or she looked young, they called him or her young even if they were actually much older. This is true in both the marriages of the Prophet (ﷺ); when he married Khadija (رضي الله عنها), even though she was 40 (i.e. 15 years older), the Prophet (ﷺ) married her and both of them standing next to each other would not and did not look odd at all as she did not look like a 40 year old that we normally assume; in fact she had many children in her 40s and may have even looked like as if she were in her late 20s.
Moreover, the society did not raise any objections as well whereas for such age gaps today, the society in general does object, at worst, and gossip around, at best. Similarly, the marriage of the Prophet (ﷺ) with Aisha (رضي الله عنها) also did not raise objections from the society back then and they too, standing next to each other would not, and did not, look odd.
A narration from Aisha (رضي الله عنها):
There are statements from the Prophet (ﷺ) that prohibit (or advise) people against colouring their hair black. Scholars have said that a person with natural black hair should not colour their white hair black but another colour and a person with hair colour other than black may do so. The reason behind this is that one may not fool others into believing that he is young while he is much older. This is natural for a society that does not rely on calendars, birth certificates, identity cards and so on. The following statement of Aisha (رضي الله عنها) explains this:
إذا خطب أحدكم المرأة وهو يخضب بالسواد فليعلم ما أنه يخضب
When one of you is going to marry a woman and has used black dye he should make it known that he has dyed.
This narration is further proof that the people in Arabia at/before the time of the Prophet (ﷺ) did not view others by their biological ages but judged their ages based on how they looked and when the Prophet (ﷺ) married Aisha (رضي الله عنها), they both looked a matching couple.
The marriage of the Prophet (ﷺ) and Aisha (رضي الله عنها) was in an era without calendars and they did not judge each other based on ages. They looked at how the person looks and treated them accordingly. We even have cases where teenagers had led armies.
Moreover, the culture of the era then was not similar to what we have today; we have a formal education system from middle school to high school to college and more while learning was different back then. Today, if you marry a girl against the culture, it might be considered injustice to her as she misses out on schooling, friends and a lot more whereas not marrying someone young in the past was injustice to the girl and then she would have been missing out on the norm of the day and everything that comes with it. Do not compare two different eras with two different cultures. If today, the culture was to change and people married in middle or high school (provided that they matured i.e. reached puberty), there would not be objections against it and no one would cry injustice to the girl. It does not mean that our morals have improved now; it simply means that our cultures have changed over time.
To conclude, the marriage of the Prophet (ﷺ) and Aisha (رضي الله عنها) was not between two ages and that is an incorrect way to look at it; the marriage was between what people saw as a young man and a physically matured young lady who did not look odd together.
Allah knows best.
References and footnotes:
 Shannon Harrison, Melissa Piliang and Wilma explain why, when hair disorders occur: Alopecia is the general term for hair loss. Hair loss can occur from the scalp and any hair-bearing part of the body. Hair has great social and cultural importance, and patients with hair loss experience anxiety and concern…..
….The most common form of hair loss is androgenetic alopecia (pattern hair loss), which increases with age; at least 80% of white men show some degree of thinning by the age of 70 year. Androgenetic alopecia occurs with the ONSET OF PUBERTY and in males is dependent on circulating androgens. Female pattern hair loss (female androgenetic alopecia) also starts after puberty… (Current Clinical Medicine: Expert Consult – William D Carey)
Lisa Akbari: “Studies show that hair loss affects approximately one third of all women. Although hair loss is most commonly seen after menopause, it can begin as early as puberty.” (Every Woman’s Guide to Beautiful Hair at Any Age: Learn What Can Be Done to keep a beautiful head of hair for a lifetime by Lisa Akbari page 70 -71)
 Another translation for the same description is as follows:
He was innocently bright and had broad countenance. His manners were fine. Neither was his belly bulging out nor was his head deprived of hair. He had black attractive eyes finely arched by eyebrows. His hair glossy and black, inclined to curl, he wore long. His voice was extremely commanding. His head was large, well formed and set on a slender neck. His expression was pensive and contemplative, serene and sublime. The stranger was fascinated from the distance, but no sooner he became intimate with him than this fascination was changed into attachment and respect. His expression was very sweet and distinct. His speech was well set and free from the use of superfluous words, as if it were a rosary of beads. His stature was neither too high nor too small to look repulsive. He was a twig amongst the two, singularly bright and fresh. He was always surrounded by his Companions. Whenever he uttered something, the listeners would hear him with rapt attention and whenever he issued any command, they vied with each other in carrying it out. He was a master and a commander. His utterances were marked by truth and sincerity, free from all kinds of falsehoods and lies. [Source]
 I have personally encountered such situations and I am sure many others would have as well where I asked an apparently teenage boy as to what grade he studied in and got a reply that he was in his 30s. Vice versa is also true; I had a classmate at age 11/12 who had a beard with a much mature built and looked like someone in his 20s.
 ‘Abū al-A‘lā Mubārakpurī, Tuhfah al-Ahwadhi, vol. 5 (Beirut: Dar al-Kutub al-‘Ilmiyyah, 1990).