What is the ruling on someone who made a covenant with Allah to perform prayers on time, then was overcome by sleep and missed Fajr prayer, so he performed it after its prescribed time had passed? Is the sin lifted from him due to the saying, "The Pen has been lifted from the sleeper"?

There is no sin upon one who sleeps through their prayer, for they are not among those who are heedless of it, nor do they fall under the threat (of punishment); because the pen is lifted from them. The ruling for them is to pray it when they wake up, just as the Prophet, peace and blessings be upon him, and his companions did when they slept through the Fajr prayer. And as stated in the Hadith: "There is no negligence in sleep. Negligence is only upon one who leaves the prayer until the time of the next prayer enters."