Musnad Ahmad 27:1812

Ibn Numayr narrated to us, Hajjaj narrated to us, from ‘Ata’, and Ibn Abi Mulaykah, and from Nafi’, from Ibn ‘Umar: "That the Prophet, peace and blessings of Allah be upon him, when he entered Makkah, he touched the Black Stone and the Yemeni Corner, and he did not touch any of the corners other than them."