"The Messenger of Allah ﷺ was asked about a man who slept and missed the prayer, or forgot it. He said: 'The expiation for that is to pray it when he remembers it.'"  

سُئِلَ رَسُولُ اللَّهِ ﷺ عَنِ الرَّجُلِ يَرْقُدُ عَنِ الصَّلاَةِ أَوْ يَغْفُلُ عَنْهَا قَالَ كَفَّارَتُهَا أَنْ يُصَلِّيَهَا إِذَا ذَكَرَهَا  

"They told the Prophet ﷺ that they had slept and missed the prayer. He said: 'There is no negligence when one sleeps, rather negligence is when one is awake. If any one of you forgets a prayer or sleeps and misses it, let him pray it when he remembers it.'"  

ذَكَرُوا لِلنَّبِيِّ ﷺ نَوْمَهُمْ عَنِ الصَّلاَةِ فَقَالَ إِنَّهُ لَيْسَ فِي النَّوْمِ تَفْرِيطٌ إِنَّمَا التَّفْرِيطُ فِي الْيَقَظَةِ فَإِذَا نَسِيَ أَحَدُكُمْ صَلاَةً أَوْ نَامَ عَنْهَا فَلْيُصَلِّهَا إِذَا ذَكَرَهَا  

"The Messenger of Allah ﷺ said: 'There is no negligence when one sleeps, rather negligence is when one does not offer one prayer until the time of the next prayer comes and he realizes that he has missed a prayer.'"  

قَالَ رَسُولُ اللَّهِ ﷺ لَيْسَ فِي النَّوْمِ تَفْرِيطٌ إِنَّمَا التَّفْرِيطُ فِيمَنْ لَمْ يُصَلِّ الصَّلاَةَ حَتَّى يَجِيءَ وَقْتُ الصَّلاَةِ الأُخْرَى حِينَ يَنْتَبِهُ لَهَا