Muwatta Malik 1758

حَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ إِنَّ الْيَهُودَ إِذَا سَلَّمَ عَلَيْكُمْ أَحَدُهُمْ فَإِنَّمَا يَقُولُ السَّامُ عَلَيْكُمْ ‏.‏ فَقُلْ عَلَيْكَ ‏"‏ ‏.‏

Yahya related to me from Malik from Abdullah ibn Dinar that Abdullah ibn Umar said that the Messenger of Allah, may Allah bless him and grant him peace, said, "When a jew greets you, and says 'Death to you' (as-samu alaykum) say, 'And to you.' " Yahya said, "Malik was asked whether a person who greeted a jew or christian, should apologise for it. He said, 'No

Reference

Muwatta Malik 1758

In-book

Book 53, Hadith 3