Musnad Ahmed: Hadith 3984

We were on the campaign of Badr, each three of us to one camel, and Abu Lubabah and ‘Ali bin Abi Talib were the two who rode with the Messenger of Allah (ﷺ). It was the turn of The Messenger of Allah (ﷺ) to walk, and they said: Ride, O Messenger of Allah, and we will walk instead of you. He said: "You are not stronger than me and I am not in less need of reward than you.”