Sahih Muslim #1568 · The Book of Marriage

Sahih MuslimQatada narrated on the authority of Anas b. Malik that the Messenger of Allah
Sahih Muslim · Book 16 · The Book of Marriage
Sahih Muslim · كتاب 16 · كتاب النكاح
He who forgets the prayer, or he slept (and it was omitted), its expiation is (only) that he should observe it when he remembers it.
وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ قَالَ نَبِيُّ اللَّهِ صلى الله عليه وسلم ‏
"‏ مَنْ نَسِيَ صَلاَةً أَوْ نَامَ عَنْهَا فَكَفَّارَتُهَا أَنْ يُصَلِّيَهَا إِذَا ذَكَرَهَا ‏"‏ ‏.‏
Reference : Sahih Muslim 1568In-book reference : Book 5, Hadith 401