It was narrated from Ibn ‘Umar that ‘Umar رضي الله عنه kissed the Black Stone, then he said:

I know that you are only a stone. Were it not that I saw the Messenger of Allah (ﷺ) kiss you, I would not have kissed you.

حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ عُمَرَ، رَضِيَ اللَّهُ عَنْهُ قَبَّلَ الْحَجَرَ ثُمَّ قَالَ قَدْ عَلِمْتُ أَنَّكَ حَجَرٌ وَلَوْلَا أَنِّي رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَبَّلَكَ مَا قَبَّلْتُكَ‏.‏