Musnad Ahmad 2:243

Muhammad ibn Ubayd narrated to us, al-A’mash narrated to us, from Ibrahim, from ‘Abis ibn Rabi’ah, who said: I saw ‘Umar come to the Stone (the Black Stone), and he said: "As for me, by Allah, I know that you are a stone that neither harms nor benefits. And were it not that I saw the Messenger of Allah, may Allah bless him and grant him peace, kiss you, I would not have kissed you." Then he drew near and kissed it.