Musnad Abu Ya'la al-Mawsili 110:57

Abu Khaythama narrated to us, Sufyan narrated to us, al-Zuhri narrated to us, from 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 the Day of Sacrifice. She said: "The obligation of Allah regarding Hajj has reached my father while he is a very old man who cannot steady himself upon the mount. Do you think I should perform Hajj on his behalf?" He said: "Yes."