Musnad Ahmad 22:22

Hashim narrated to us, Yahya ibn Abi Ishaq narrated to us, from Sulayman ibn Yasar, from Abdullah ibn Abbas—or from al-Fadl ibn Abbas—that a man asked the Prophet, peace and blessings of Allah be upon him, and said: "O Messenger of Allah, my father reached Islam while he was a very old man who cannot remain steady on his mount. Should I perform Hajj on his behalf?" He said: "Do you see, if he had a debt upon him and you paid it off on his behalf, would it suffice him?" He said: "Yes." He said: "Then perform Hajj on behalf of your father."