The Jews used to greet the Prophet ﷺ by saying, "As-Samu 'Alaika (i.e., death be upon you), so I understood what they said, and I said to them, "As-Samu 'alaikum wal-la'na (i.e. Death and Allah's Curse be upon you)." The Prophet ﷺ said, "Be gentle and calm, O ʿAisha, as Allah likes gentleness in all affairs." I said, "O Allah's Prophet! Didn't you hear what they said?" He said, "Didn't you hear me answering them back by saying, 'Alaikum (i.e., the same be upon you)?"
كَانَ الْيَهُودُ يُسَلِّمُونَ عَلَى النَّبِيِّ ﷺ يَقُولُونَ السَّامُ عَلَيْكَ فَفَطِنَتْ عَائِشَةُ إِلَى قَوْلِهِمْ فَقَالَتْ عَلَيْكُمُ السَّامُ وَاللَّعْنَةُ فَقَالَ النَّبِيُّ ﷺ مَهْلاً يَا عَائِشَةُ إِنَّ اللَّهَ يُحِبُّ الرِّفْقَ فِي الأَمْرِ كُلِّهِ فَقَالَتْ يَا نَبِيَّ اللَّهِ أَوَلَمْ تَسْمَعْ مَا يَقُولُونَ قَالَ أَوَلَمْ تَسْمَعِي أَنِّي أَرُدُّ ذَلِكَ عَلَيْهِمْ فَأَقُولُ وَعَلَيْكُمْ