When the People of the Book offer you salutations, you should say: The same to you.  

قَالَ رَسُولُ اللَّهِ ﷺ ح وَحَدَّثَنِي إِسْمَاعِيلُ بْنُ سَالِمٍ حَدَّثَنَا هُشَيْمٌ أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ أَبِي بَكْرٍ عَنْ جَدِّهِ أَنَسِ بْنِ مَالِكٍ أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا سَلَّمَ عَلَيْكُمْ أَهْلُ الْكِتَابِ فَقُولُوا وَعَلَيْكُمْ  

The People. of the Book offer us salutations (by saying as-Salamu- 'Alaikum). How should we reciprocate them? Thereupon he said: Say: Wa 'Alaikum (and upon you too).  

عَنْ أَنَسٍ أَنَّعليه وسلم قَالُوا لِلنَّبِيِّ ﷺ إِنَّ أَهْلَ الْكِتَابِ يُسَلِّمُونَ عَلَيْنَا فَكَيْفَ نَرُدُّ عَلَيْهِمْ قَالَ قُولُوا وَعَلَيْكُمْ  

When the Jews offer you salutations, some of them say as-Sam-u-'Alaikum (death be upon you). You should say (in response to it): Let it be upon you.  

قَالَ رَسُولُ اللَّهِ ﷺ إِنَّ الْيَهُودَ إِذَا سَلَّمُوا عَلَيْكُمْ يَقُولُ أَحَدُهُمُ السَّامُ عَلَيْكُمْ فَقُلْ عَلَيْكَ  

This hadith has been narrated on the authority of Ibn 'Umar through another chain of transmitters with a slight variation of wording.  

عَنِ النَّبِيِّ ﷺ بِمِثْلِهِ غَيْرَ أَنَّهُ قَالَ فَقُولُوا وَعَلَيْكَ  

As-Sam-u-'Alaikum. A'isha said in response: As-Sam-u-'Alaikum (death be upon you) and curse also, whereupon Messenger of Allah ﷺ said: 'A'isha, verily Allah loves kindness in every matter. She said: Did you bear what they said? Thereupon he said: Did you not hear that I said (to them): Wa 'Alaikum.  

قَالَتِ اسْتَأْذَنَ رَهْطٌ مِنَ الْيَهُودِ عَلَى رَسُولِ اللَّهِ ﷺ فَقَالُوا السَّامُ عَلَيْكُمْ فَقَالَتْ عَائِشَةُ بَلْ عَلَيْكُمُ السَّامُ وَاللَّعْنَةُ فَقَالَ رَسُولُ اللَّهِ ﷺ يَا عَائِشَةُ إِنَّ اللَّهَ يُحِبُّ الرِّفْقَ فِي الأَمْرِ كُلِّهِ قَالَتْ أَلَمْ تَسْمَعْ مَا قَالُوا قَالَ قَدْ قُلْتُ وَعَلَيْكُمْ  

I said 'Alaikum, and the transmitter did not make mention of the word "and".  

عَنِ الزُّهْرِيِّ بِهَذَا الإِسْنَادِ وَفِي حَدِيثِهِمَا جَمِيعًا قَالَ رَسُولُ اللَّهِ ﷺ قَدْ قُلْتُ عَلَيْكُمْ وَلَمْ يَذْكُرُوا الْوَاوَ  

Abu'l-Qasim (the Kunya of the Holy Prophet), as-Sam-u-'Alaikum, whereupon he (the Holy Prophet) said: Wa 'Alaikum. A'isha reported: In response to these words of theirs, I said: But let there be death upon you and disgrace also, whereupon Messenger of Allah ﷺ said: 'A'isha, do not use harsh words. She said: Did you hear what they said? Thereupon he (the Holy Prophet) said: Did I not respond to them when they said that; I said to them: Wa 'Alaikum (let it be upon you).  

أَتَى النَّبِيَّ ﷺ أُنَاسٌ مِنَ الْيَهُودِ فَقَالُوا السَّامُ عَلَيْكَ يَا أَبَا الْقَاسِمِ قَالَ وَعَلَيْكُمْ قَالَتْ عَائِشَةُ قُلْتُ بَلْ عَلَيْكُمُ السَّامُ وَالذَّامُ فَقَالَ رَسُولُ اللَّهِ ﷺ يَا عَائِشَةُ لاَ تَكُونِي فَاحِشَةً فَقَالَتْ مَا سَمِعْتَ مَا قَالُوا فَقَالَ أَوَلَيْسَ قَدْ رَدَدْتُ عَلَيْهِمُ الَّذِي قَالُوا قُلْتُ وَعَلَيْكُمْ  

'A'isha. (do not do that) for Allah does not like the use of harsh words, and it was at this stage that this verse of Allah. the Exalt. ed and Glorious. was revealed:" And when they come to thee, they greet thee with a greeting with which Allah greets thee not" (Iviii. 8) to the end of the verse.  

رَسُولُ اللَّهِ ﷺ مَهْ يَا عَائِشَةُ فَإِنَّ اللَّهَ لاَ يُحِبُّ الْفُحْشَ وَالتَّفَحُّشَ وَزَادَ فَأَنْزَلَ اللَّهُ ﷻ { وَإِذَا جَاءُوكَ حَيَّوْكَ بِمَا لَمْ يُحَيِّكَ بِهِ اللَّهُ} إِلَى آخِرِ الآيَةِ  

Wa 'Alaikum, A'isha was enraged and asked him (Allah's Apostle) whether he had not heard what they had said. He said, I did hear and I retorted to them (and the curse that I invoked upon them would receive response from Allah), but (the curse that they invoked upon us) would not be responded.  

أَنَّهُ سَمِعَ جَابِرَ بْنَ عَبْدِ اللَّهِ يَقُولُ سَلَّمَ نَاسٌ مِنْ يَهُودَ عَلَى رَسُولِ اللَّهِ ﷺ فَقَالُوا السَّامُ عَلَيْكَ يَا أَبَا الْقَاسِمِ فَقَالَ وَعَلَيْكُمْ فَقَالَتْ عَائِشَةُ وَغَضِبَتْ أَلَمْ تَسْمَعْ مَا قَالُوا قَالَ بَلَى قَدْ سَمِعْتُ فَرَدَدْتُ عَلَيْهِمْ وَإِنَّا نُجَابُ عَلَيْهِمْ وَلاَ يُجَابُونَ عَلَيْنَا  

Do not greet the Jews and the Christians before they greet you and when you meet any one of them on the roads force him to go to the narrowest part of it.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ تَبْدَءُوا الْيَهُودَ وَلاَ النَّصَارَى بِالسَّلاَمِ فَإِذَا لَقِيتُمْ أَحَدَهُمْ فِي طَرِيقٍ فَاضْطَرُّوهُ إِلَى أَضْيَقِهِ  

'When you meet the People of the Book." And in the hadith transmitted on the authority of Jarir the words are:" When you meet them," but none amongst the polytheists has been mentioned explicitly by name.  

فِي أَهْلِ الْكِتَابِ وَفِي حَدِيثِ جَرِيرٍ إِذَا لَقِيتُمُوهُمْ وَلَمْ يُسَمِّ أَحَدًا مِنَ الْمُشْرِكِينَ