Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) said: "Whatever disease Allah has created, He has also placed a cure for it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19557
Sayyiduna Jabir (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that the Messenger of Allah (peace and blessings be upon him) said: "For every disease there is a medicine; when the right medicine reaches the disease, the sick person recovers by the permission of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19558
Sayyiduna Usamah bin Sharik (may Allah be pleased with him) says: I came to the Messenger of Allah (peace and blessings be upon him), and the Companions (may Allah be pleased with them) were sitting as though birds were perched on their heads. I gave the greeting of peace and sat down. Then a Bedouin came and said: "O Messenger of Allah! Shall we treat ourselves with medicine?" He (peace and blessings be upon him) said: "Seek treatment, for Allah has placed a cure for every disease, except old age." The narrator says: He asked about some other things, and he (peace and blessings be upon him) said: "There is no harm." He (peace and blessings be upon him) said: "Servants of Allah! Allah has removed hardship, except for the one who wrongs others; that is a cause of ruin and distress." He said: "O Messenger of Allah! What is the best thing that people have been given?" He (peace and blessings be upon him) said: "Good character."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19559
Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) said: "Allah has sent down a cure for every disease; whoever came to know it, knew it, and some people remain unaware of it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19560