Musnad Ahmad 25:53

Sufyan narrated to us, from al-Zuhri, who heard Sulayman ibn Yasar, from Ibn Abbas, that a woman from Khath'am asked the Messenger of Allah, may Allah bless him and grant him peace, on the morning of Jam' (Muzdalifah), while al-Fadl ibn Abbas was riding behind him. She said: "The obligation of Allah regarding Hajj upon His servants has reached my father, who is a very old man, unable to remain steady on the mount. Do you think I should perform Hajj on his behalf?" He said: "Yes."