Which Surah was revealed in its entirety to the Messenger (peace and blessings be upon him) while he was on the back of his mount?

Perhaps the surah intended by (A surah has been revealed to me that is dearer to me than all that the sun has risen upon) is Surah Al-Fath. It is mentioned in Sahih Muslim that the Prophet, may Allah bless him and grant him peace, recited it in the year of the Conquest (Fath). In Al-Bukhari, it is narrated that Umar ibn Al-Khattab asked the Prophet, may Allah bless him and grant him peace, several times, but he did not answer him. Umar feared that a Qur'anic verse had been revealed about him. Then the Prophet, may Allah bless him and grant him peace, called him to inform him that a surah had been revealed to him that was dearer to him than all that the sun had risen upon, and he recited to him: "Indeed, We have granted you a clear triumph (fath)." Ahmad also narrated that the Prophet recited Surah Al-Fath during his journey in the year of the Conquest.