The Messenger of Allah ﷺ said, "On the night I was taken on the night journey, I passed by Musa and saw him standing in prayer in his grave."
حدثنا وكيع حدثنا سفيان عن سليمان التيمي
قال رسول الله ﷺ مررت ليلة أسري بي على موسى فرأيته قائما يصلي في قبره
Its isnad is sahih. Muslim narrated it, 4/1845, no. 2375, in the Book of Virtues, chapter on the virtues of Musa , and Nasai, 3/216, no. 1634, in the Book of Night Prayer, chapter mentioning the prayer of the Prophet of Allah, Musa
.