Sunan an-Nasa'i 2937
سنن النسائي#2937SahihIt was narrated Abbas bin Rabiah said:"I saw Umar coming to the Stone and saying: 'I know that you are just a stone; had I not seen the Messenger of Allah kiss you I would not have kissed you.' Then he came close to it and kissed it." (Sahih) Chpater 148. How to Kiss It
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 24:320