حَدَّثَنَا مُحَمَّدُ بْنُ عُبَيْدٍ، حَدَّثَنَا الْأَعْمَشُ، عَنْ إِبْرَاهِيمَ، عَنْ عَابِسِ بْنِ رَبِيعَةَ
قَالَ رَأَيْتُ عُمَرَ رَضِيَ اللَّهُ عَنْهُ أَتَى الْحَجَرَ فَقَالَ: أَمَا وَاللَّهِ إِنِّي لَأَعْلَمُ أَنَّكَ حَجَرٌ لَا تَضُرُّ وَلَا تَنْفَعُ وَلَوْلَا أَنِّي رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَبَّلَكَ مَا قَبَّلْتُكَ ثُمَّ دَنَا فَقَبَّلَهُ
I saw Umar go to the Black Stone and say: By Allah, I know that you are a stone and cannot cause harm or bring benefit. Were it not that I saw the Messenger of Allah (sallallahu alayhi wa sallam) kiss you, I would not have kissed you. Then he leant down and kissed it.
Musnad Ahmad 308, Book 2, Musnad `Umar b. al-Khattab (ra), Hadith 231. 1 min read