Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: Fadl bin Abbas (may Allah be pleased with him) was riding behind the Messenger of Allah (peace and blessings be upon him) when a woman from the tribe of Khath'am came and began asking him for a ruling. Fadl (may Allah be pleased with him) began looking at her and she began looking at Fadl (may Allah be pleased with him), so the Messenger of Allah (peace and blessings be upon him) turned the face of Fadl (may Allah be pleased with him) to the other side. The woman said: The obligation of Hajj from Allah Almighty has reached my honoured father in a state where he cannot sit on a mount; shall I perform Hajj on his behalf? He (peace and blessings be upon him) said: "Yes." This was during the Farewell Pilgrimage.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 8625