حَدَّثَنَا أَبُو مُعَاوِيَةَ، حَدَّثَنَا عَاصِمٌ الْأَحْوَلُ، عَنْ عَبْدِ اللَّهِ بْنِ سَرْجِسَ
قَالَ رَأَيْتُ الْأُصَيْلِعَ يَعْنِي عُمَرَ رَضِيَ اللَّهُ عَنْهُ يُقَبِّلُ الْحَجَرَ وَيَقُولُ إِنِّي لَأُقَبِّلُكَ وَأَعْلَمُ أَنَّكَ حَجَرٌ لَا تَنْفَعُ وَلَا تَضُرُّ وَلَوْلَا أَنِّي رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُقَبِّلُكَ لَمْ أُقَبِّلْكَ
I saw the bald one, meaning Umar (رضي الله عنه), kiss the [Black) Stone and say: I am kissing you and I know that you are only a stone and cannot bring any benefit or ward off any harm, were it not that I saw the Messenger of Allah رضي الله عنه kiss you, I would not have kissed you.
Musnad Ahmad 222, Book 2, Musnad `Umar b. al-Khattab (ra), Hadith 145. 1 min read