Whoever sleeps through or has forgotten to pray a certain prayer should pray it when he wakes up or remembers the prayer. Abu Qatadah related that sleeping through the prayer time was mentioned to the Prophet, upon whom be peace, and he said, “There is no negligence in sleep, but negligence occurs while one is awake. If one of you forgets a prayer or sleeps through its time, then he should pray it when he remembers it.”
As to the authenticity of the report, it is recorded by an-Nasa’i and at-Tirmizhi, who said it is sahih.
Anas related that the Prophet, upon whom be peace, said, “Whoever forgets a prayer should pray it when he remembers it, and there is no expiation for it save that.” (Related by al-Bukhari and Muslim.) Reported ‘Imran ibn Husain, “We went with the Messenger of Allah during the night. When the last portion of the night came, we became tired and fell asleep. We did not wake until we felt the heat of the sun. Some of us tried hurriedly to purify ourselves. The Prophet ordered us to be calm. Then we rode on until the sun had risen and we made ablution. He ordered Bilal to make the call to prayer, and then prayed two rak’ah before the (obligatory) morning prayer. Then we stood and prayed. We said, ‘O Messenger of Allah, should we not repeat it tomorrow in its proper time?’ He said, ‘Would your Lord the Most High forbid you from interest and accept it from you?”‘ (Related by Ahmed and others.)