Abu Qatadah reported: It was mentioned to the Prophet, peace and blessings be upon him, that some of them missed the prayer while they slept and the Prophet said, “It is not neglectful if missed (unintentionally) because of sleep. Verily, it is only neglectful if missed while awake. If one of you forgets to pray or misses it by sleeping, let him pray it as soon as he remembers.”
Source: Sunan al-Tirmidhī 177
Grade: Sahih (authentic) according to Al-Tirmidhi
عَنْ أَبِي قَتَادَةَ قَالَ ذَكَرُوا لِلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ نَوْمَهُمْ عَنْ الصَّلَاةِ فَقَالَ إِنَّهُ لَيْسَ فِي النَّوْمِ تَفْرِيطٌ إِنَّمَا التَّفْرِيطُ فِي الْيَقَظَةِ فَإِذَا نَسِيَ أَحَدُكُمْ صَلَاةً أَوْ نَامَ عَنْهَا فَلْيُصَلِّهَا إِذَا ذَكَرَهَا
177 سنن الترمذي كتاب الصلاة باب ما جاء في النوم عن الصلاة
177 المحدث الترمذي خلاصة حكم المحدث حسن صحيح في سنن الترمذي