Sahih Adab al-Mufrad

791/1023- (Authentic chain of narration) From Abdullah ibn Amr who said: While we were sitting with the Prophet, peace be upon him, in the shade of a tree between Mecca and Medina—a Bedouin came, one of the roughest and harshest of people, and said: Peace be upon you. They replied: "And upon you [السلام]."

792/1033- (Authentic chain) From Abu Jamrah(1): "I heard Ibn Abbas, when greeted with salam, say: 'And upon you, and the mercy of Allah.'"

793/1034- (Hasan Sahih) Abu Abdullah said: Qeila said: A man said: Peace be upon you, O Messenger of Allah! He said: "And upon you be peace, and the mercy of Allah."

794/1035- (Sahih) From Abu Dharr who said: I came to the Prophet, peace be upon him, when he had finished his prayer, and I was the first to greet him with the greeting of Islam. He said: "And upon you, and the mercy of Allah. From whom are you?" I said: From Ghifar.

795/1037- (Sahih) From Muawiya ibn Qurra who said: My father said to me: "O my son! If a man passes by you and says: 'As-salamu alaykum,' do not say: 'Wa alayk,' as if you are specifying him alone; for he is not alone, but rather say: 'As-salamu alaykum.'"