Sayyiduna Uqbah bin Amir (may Allah be pleased with him) — who was in charge of the white (Shahba') mule of the Messenger of Allah (peace and blessings be upon him) and used to lead it by the front on journeys — said: I was leading the Messenger of Allah (peace and blessings be upon him), who was on his mount, during a part of the night. Then the Messenger of Allah (peace and blessings be upon him) said: "Make it kneel." So I made it kneel, and he dismounted from his mount, then said: "O Uqbah! Mount." I said: Subhan Allah! On your mount (how can I ride)? He (peace and blessings be upon him) again commanded me and said: "Mount." I repeated the same thing, and I kept doing so again and again until I feared that I would end up disobeying the Messenger of Allah (peace and blessings be upon him), so I mounted his mount. Then he (peace and blessings be upon him) urged his she-camel to rise and it stood up. Then the Messenger of Allah (peace and blessings be upon him) called me in one of the mountain passes and said: "O Uqbah! Shall I not teach you two surahs of the Qur'an which are among the most excellent surahs of the Qur'an, or among the very most excellent?" I said: Certainly, may my father and mother be ransomed for you. So he (peace and blessings be upon him) taught me the Mu'awwidhatayn (the two surahs of seeking refuge). Then he said: "O Uqbah! When you see the dawn, inform me." When I saw the dawn, I said: O Messenger of Allah! This is the dawn. So he (peace and blessings be upon him) made his mount kneel, then performed ablution, then established the prayer, then took me by the hand and placed me on his right, and recited these two surahs in the morning prayer. Then he turned to me and said: "O Uqbah! Recite them whenever you stand and whenever you sleep."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14999