It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that on the day of Badr we used to ride by turns, three people to one camel. Sayyiduna Ali (may Allah be pleased with him) and Sayyiduna Abu Lubabah (may Allah be pleased with him) were the companions of the Messenger of Allah (peace and blessings be upon him) (taking turns on the same camel). When it was the turn of the Messenger of Allah (peace and blessings be upon him) to walk, the two of them would say: You (peace and blessings be upon him) stay mounted and we will walk in your place. He (peace and blessings be upon him) would say: "I am no less in need of the reward than you two, nor are you two stronger at walking than I am." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.