Messenger of Allah ﷺ said, "When the Jews greet anyone of you they say: 'Sam'Alaika (death be upon you); so you should say; 'Wa 'Alaika (and upon you).'" (Using translation from Bukhārī 6928)
عَنِ النَّبِيِّ ﷺ قَالَ إِنَّ الْيَهُودَ إِذَا سَلَّمُوا قَالُوا السَّامُ عَلَيْكُمْ فَقُولُوا وَعَلَيْكُمْ