Sunan an-Nasa'i, Volume 2, Book 20, Hadith 1638 (DarusSalam) ⓘ
It was narrated from Anas, from on of the companions of the Prophet, that: The Prophet said: 'On the night on which I was taken on the Night Journey, I passed by Musa and he was praying in his grave.'
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، عَنْ سُلَيْمَانَ، عَنْ أَنَسٍ، عَنْ بَعْضِ، أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " لَيْلَةَ أُسْرِيَ بِي مَرَرْتُ عَلَى مُوسَى وَهُوَ يُصَلِّي فِي قَبْرِهِ " .
also referenced under: Hadith 1637 (Reference) & Book 20, Hadith 40 (In-Book)