Sunan an-Nasa'i 1633
سنن النسائي#1633Sahihأَخْبَرَنِي أَحْمَدُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا حَبَّانُ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، قَالَ أَنْبَأَنَا ثَابِتٌ، وَسُلَيْمَانُ التَّيْمِيُّ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " مَرَرْتُ عَلَى قَبْرِ مُوسَى عَلَيْهِ السَّلاَمُ وَهُوَ يُصَلِّي فِي قَبْرِهِ " .
It was narrated from Anas that:The Prophet (ﷺ) said: "I passed by the grave of Musa, peace be upon him, and he was praying in his grave
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 20:36