The Prophet ﷺ said, "When a Jew greets you, he is actually saying, 'Death be upon you,' so respond with, 'And upon you.'"On another occasion he said, "When the Jews greet you, say, 'And upon you,' for they say, 'Death be upon you.'"
حدثنا سفيان سمعته من ابن دينار
عن النبي ﷺ إذا سلم عليك اليهودي فإنما يقول السام عليك فقل وعليك وقال مرة إذا سلم عليكم اليهود فقولوا وعليكم فإنهم يقولون السام عليكم
Its isnad is sahih. Malik also related it in Muwatta 3:132 from Abdullah bin Dinar, and Abu Dawud related it similarly in 4:519 through Abdul-Aziz bin Muslim from Abdullah bin Dinar. Bukhari, Muslim, Tirmidhi, and Nasai also recorded it, as noted in Awn al-Mabud citing Tirmidhi.