Anas reported God's Messenger as saying, “If anyone forgets a stated prayer or oversleeps, expiation is made by observing it when he remembers it.” A version has “That is the only expiation for it.”
He also reported God’s Messenger as saying, “If any of you performs a sajda of the afternoon prayer before sunset, he should complete his prayer; and if he is present at a sajda of the Morning Prayer before sunrise, he should complete his prayer.”
Abu Qatada reported God’s Messenger as saying, “There is no remissness in sleep, it is only when one is awake that there is remissness; so when any of you forgets a stated prayer or oversleeps, he should observe it when he remembers it, for God has said, ‘And observe the prayer for remembrance of Me’” (Al-Qur’an, 20:14).
Abu Huraira reported God’s Messenger as saying, “If anyone performs a rak'a of the Morning Prayer before sunrise, he has observed the Morning Prayer; and if anyone performs a rak'a of the afternoon prayer before sunset, he has observed the afternoon prayer.”
