Musnad Ahmad 33:1144

Sulayman ibn Dawud narrated to us, Abd al-Rahman narrated to us, from Musa ibn Uqbah, from Abu al-Zubayr, from Jabir, who said: "There were images in the Kaaba, so the Prophet, may God bless him and grant him peace, ordered Umar ibn al-Khattab to erase them. Umar wetted a cloth and erased them with it. Then the Messenger of God, may God bless him and grant him peace, entered it, and there was nothing left of them inside it."