Sunan Abi Dawud, Hadith 1868

Abis bin Rabi’ah said on the authority of ‘Umar He(‘Umar) came to the (Black) Stone and said “ I know for sure that you are a stone which can neither benefit nor injure and had I not seen the Apostle of Allaah kissing you, I would not have kissed you.”

حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، أَخْبَرَنَا سُفْيَانُ، عَنِ الأَعْمَشِ، عَنْ إِبْرَاهِيمَ، عَنْ عَابِسِ بْنِ رَبِيعَةَ، عَنْ عُمَرَ، أَنَّهُ جَاءَ إِلَى الْحَجَرِ فَقَبَّلَهُ فَقَالَ إِنِّي أَعْلَمُ أَنَّكَ حَجَرٌ لاَ تَنْفَعُ وَلاَ تَضُرُّ وَلَوْلاَ أَنِّي رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يُقَبِّلُكَ مَا قَبَّلْتُكَ ‏.‏

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also referenced under: Hadith 1873 (DarusSalam)