It is narrated from Sayyiduna al-Zubayr (may Allah be pleased with him) that he said: I saw the Prophet (peace and blessings be upon him) when he (peace and blessings be upon him) went to climb up to the rock, and the Prophet (peace and blessings be upon him) was wearing two coats of mail that day, and he (peace and blessings be upon him) was unable to climb. So Sayyiduna Talhah bin Ubaydullah (may Allah be pleased with him) sat down beneath him (peace and blessings be upon him), and he raised the Messenger of Allah (peace and blessings be upon him) up until he settled on it. The Messenger of Allah (peace and blessings be upon him) said: "Talhah has made it obligatory (awjaba)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 13099