((إذَا سَلَّمَ عَلَيْكُمْ أَهْلُ الْكِتَابِ فَقُولُوا: وَعَلَيْكُمْ)).
Translation
(When the people of the Book greet you, reply by saying: (And upon you.))
Source
Hisnul Muslim (Fortress of the Muslim), No. 227 — chapter “How to reply to a disbeliever if he says Salam to you”. hisnmuslim.com
Related Duas
((إِذَا عَطَسَ أَحَدُكُم فَلْيَقُلِ الْحَمْدُ لِلَّهِ، وَلْيَقُلْ لَهُ أَخُوهُ أَوْ صَاحِبُهُ: يَرْحَمُكَ اللَّهُ، فَإِذَا قَالَ لَهُ: يَرحَمُكَ اللَّهُ، فَلْيَقُلْ: يَهْدِيكُمُ اللَّهُ وَيُصْلِحُ بَالَكُمْ)).
(When one of you sneezes he should say:(All praise if for Allah.) and his brother or companion should say to him: (May Allah have mercy upon you.) and he (i.e. the one who sneezed) replies back to him:(May Allah guide yo…
Hisnul Muslim · No. 188
((يَهْدِيكُمُ اللَّهُ وَيُصْلِحُ بَالَكُمْ)).
(May Allah guide you and rectify your condition.)
Hisnul Muslim · No. 189
((أَعُوذُ بِاللَّهِ مِنَ الشَّيْطَانِ الرَّجِيمِ)).
(I take refuge with Allah from the accursed devil.)
Hisnul Muslim · No. 193