Sahih Muslim Book 26, Hadith Number 5385.

Chapter : Prohibition of saying first as-Salam-u-Alaikum to the people of the book, and how their salutations should be responded.

This hadith has been transmitted on the authority of Zuhri that Allah’s Messenger (may peace be upon him) said: I said ‘Alaikam, and the transmitter did not make mention of the word “and”.