The Messenger of Allah ﷺ said, "When one of the People of the Book greets you with peace, respond by saying, 'And upon you.'"
حدثنا أبو بكر حدثنا عبدة بن سليمان ومحمد بن بشر عن سعيد عن قتادة
قال رسول الله ﷺ إذا سلم عليكم أحد من أهل الكتاب فقولوا وعليكم
Sourcing. [Its chain of transmission is sahih] Ibn Hibban transmitted it in Mawarid, no. 1941, from the hadith of Saeed with this wording, and it also appears in Musannaf, vol. 8, p. 442. Saeed was followed by Shubah in the version narrated by Muslim (in the chapter on the prohibition of initiating a greeting to the People of the Book, and so on), no. 2163, and there is another route for it in Bukhari, no. 6926, as well as in Muslim and others, on the authority of Anas.