Did the the prophet of Islam say that black seeds can cures diseases?
All Praise to Allah Subhanahu wa Taala and blessings of Him be on Prophet Muhammad peace be upon him His family and companions,
Yeah it is true,
Abu Hurairah narrated that the Messenger of Allah (s.a.w) said: "Use this black seed. For indeed it contains a cure for every disease except As-Sam" And As-Sam is death.(Tirmidhi)
Abu Hurairah narrated that he heard the Messenger of Allah (ﷺ) say: “In black seed there is healing for every disease, except the Sam.” "Sam means death. And black seed is Shuwniz."(Ibn Majah)
Allah Swt and His Messenger knows best.
Yes, there are many hadiths that say this. Narrated Abu Huraira:
I heard Allah's Messenger (ﷺ) saying, "There is healing in black cumin for all diseases except death." Reference: Sahih al-Bukhari 5688
Abu Hurairah narrated that the Messenger of Allah (s.a.w) said: "Use this black seed. For indeed it contains a cure for every disease except As-Sam" And As-Sam is death.
Grade: Sahih, Reference: Tirmidhi, Vol. 4, Book 2, Hadith 2041
It was narrated that ‘Uthman bin ‘Abdul-Malik said: “I heard Salim bin ‘Abdullah narrating from his father that the Messenger of Allah (ﷺ) said: ‘You should eat this black seed, for in it there is healing from every disease, except the Sam (death).’” -- Source
Narrated Khalid bin Sad: We went out and Ghalib bin Abjar was accompanying us. He fell ill on the way and when we arrived at Medina he was still sick. Ibn Abi 'Atiq came to visit him and said to us, "Treat him with black cumin. Take five or seven seeds and crush them (mix the powder with oil) and drop the resulting mixture into both nostrils, for `Aisha has narrated to me that she heard the Prophet (ﷺ) saying, 'This black cumin is healing for all diseases except As-Sam.' Aisha said, 'What is As-Sam?' He said, 'Death."
Reference: Sahih al-Bukhari 5687
P.S There is, in fact, some scientific evidence to suggest that black seed might help boost the immune system and thereby acts as a remedy for all diseases. WebMD writes regarding the use of black seed for medical purposes:
Today, black seed is used for treating digestive tract conditions including gas, colic, diarrhea, dysentery, constipation, and hemorrhoids. It is also used for respiratory conditions including asthma, allergies, cough, bronchitis, emphysema, flu, swine flu, and congestion.
Other uses include lowering blood pressure, lowering cholesterol levels, treating cancer, and boosting the immune system.
...There is some scientific evidence to suggest that black seed might help boost the immune system, fight cancer, prevent pregnancy, and lessen allergic reactions by acting as an antihistamine...