(6) The Book of the Times (of Prayer)
كتاب المواقيت
(52) Chapter: Concerning One Who Forgets A Prayer
(52) باب فِيمَنْ نَسِيَ صَلاَةً
Sunan an-Nasa'i 613 
It was narrated that Anas said:
The Messenger of Allah (ﷺ) said: "Whoever forgets a prayer, let him pray it when he remembers it."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ مَنْ نَسِيَ صَلاَةً فَلْيُصَلِّهَا إِذَا ذَكَرَهَا ‏"‏ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan an-Nasa'i 613
In-book reference : Book 6, Hadith 120
English translation : Vol. 1, Book 6, Hadith 614