Al-Adab Al-Mufrad, Book 44, Hadith 15 (In-Book) ⓘ

'Abdu'r-Rahman said, "Ibn 'Umar passed by a Christian who greeted him and Ibn 'Umar returned the greeting He was told that the man was a Christian. When he learned that, he went back to him and said, 'Give me back my greeting.'"

حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، قَالَ‏:‏ أَخْبَرَنَا سُفْيَانُ، عَنْ أَبِي جَعْفَرٍ الْفَرَّاءِ، عَنْ عَبْدِ الرَّحْمَنِ قَالَ‏:‏ مَرَّ ابْنُ عُمَرَ بِنَصْرَانيٍّ فَسَلَّمَ عَلَيْهِ، فَرَدَّ عَلَيْهِ، فَأُخْبِرَ أَنَّهُ نَصْرَانِيٌّ، فَلَمَّا عَلِمَ رَجَعَ إِلَيْهِ فَقَالَ‏:‏ رُدَّ عَلَيَّ سَلامِي‏.‏