Sahih Muslim | Book 7 | Hadith Number 2913

Narrated by Ibn 'Umar (Allah be pleased with them)
Ibn 'Umar (Allah be pleased with them) reported that Umar (Allah be pleased with him) kissed the Stone and said: I am kissing you, whereas I know that you are a stone, but I saw Allah's Messenger (may peace be upon him) kissing you (that Is why I kiss you).