There is a saying of Prophet Muhammad (ﷺ) that is alleged to contradict science and logic.
في الحبة السوداء شفاء من كل داء، إلا السام
Narrated Abu Huraira: I heard Allah’s Apostle saying, “There is healing in black cumin for all diseases except death.“
There are two aspects to the narration. The first aspect is linguistic and the other being scientific. It must be understood what the Hadith actually means linguistically. When it is said that black cumin has cure for all diseases except death, one would naturally ask the question whether death is a disease or not. Death is not a disease and hence the statement itself is clear that it is not to be read and understood literally but rather as a figure of speech. This figure of speech lays down the immense importance of the black cumin.
Another important point here is the understanding of all when the diseases are mentioned. The Arabic language has a rule known as taqleeb (تقليب) which states that whenever a majority is addressed, relevant words related to them are used which automatically include the minority not directly addressed. Hence, if the Hadith states that black cumin has cure for all diseases, it applies the rule of taqleeb.
Moreover, something carrying healing does not necessarily mean that it would ‘itself’ provide healing. If, for example, acetaminophen is an ingredient in many of the medicines, it does not mean that consuming it would provide one with healing. Dr. Zaghlool el-Naggar states regarding the Hadith:
This Prophetic hadith has urged many Muslim scholars and physicians throughout the ages to carry out research about the possibility of making use of this blessed seed in the treatment of some diseases, as the word ‘heal’, is mentioned in these Ahadith (sayings of the Prophet) in an indefinite form . Some scholars assert that it is not meant to heal any disease (on its own) and that the expected percentage of cure varies according to the type of disease and its intensity.
Prophet Muhammad (ﷺ) had stated this fact about the cumin seed a long time back and the guidance provided is for mankind for all times.
The scholars have explained the Hadith as follows:
قال النووي في شرح صحيح مسلم: “وقد ذكر الخطابي في الكلام على السنن أن هذا من العام المراد به الخصوص؛ إذ لا يجتمع في طبيعة نبات واحد يجمع القوى التي تتقاوم الطبائع فيها من معالجة الأدواء على اختلافها وتقابل طبائعها، وإنما أراد أنه شفاء من كل داء يحدث من كل البرودة والرطوبة والبلغم
Imam an-Nawawi in his commentary on Saheeh Muslim said: Al-Khattabi in his Sunan mentioned that the rhetorical device of speaking in general terms, yet intending by it a specific thing, is being utilized here. There is not a single type of plant, which contains the cure for a disease and a cure for another disease which requires the opposite of that which is present in the same plant. Rather, what he intended is that it’s a healing from every disease which occurs from every cold, humidity and expectoration.
قال أبو بكر بن العربي: العسل عند الأطباء أقرب إلى أن يكون دواء من كل داء من الحبة السوداء، ومع ذلك فإن من الأمراض ما لو شرب صاحبه العسل لتأذى به، فإن كان المراد بقوله في العسل” فيه شفاء للناس” الأكثر الأغلب فحمل الحبة السوداء على ذلك أولى. وقال غيره: كان النبي -صلى الله عليه وسلم- يصف الدواء بحسب ما يشاهده من حال المريض، فلعل قوله في الحبة السوداء وافق مرض من مزاجه بارد، فيكون معنى قوله «شفاء من كل داء»؛ أي: من هذا الجنس الذي وقع القول فيه، والتخصيص بالحيثية كثير وشائع”
Abu Bakr Ibn al-‘ Arabi said: Honey according to the doctors is more worthy of being considered a healing for every disease than the black cumin, nevertheless there are still certain diseases which would worsen if the patient were to drink the honey. If in His saying “in it there is healing for people” [16:69] we understand that this refers to the majority of the cases, then restricting the Hadith of the black cumin to this as well would be even more suitable. Others have said: The Prophet (ﷺ) used to prescribe medicine in accordance with what he observed from the state of the patient. It’s possible that his statement regarding the black cumin corresponded to diseases resulting from a cold, hence the meaning of his statement “healing for all diseases” entails it being in reference to this specific nature and type of disease (i.e. related to cold). Specification of general statements in accordance with the viewpoint and perspective of the speaker is very common.
Indeed, Allah knows the best.
 Sahih al-Bukhari, vol. 7, book 71, no. 592
 Commentary on Sahih Muslim by Imam Nawwawi
 Ibn Hajar al-Asqalani’s commentary of Sahih Bukhari, Fath al-Bari