I came. And in the narration transmitted on the authority of Haddib (the words are): I happened to pass by Moses on the occasion of the Night journey near the red mound (and found him) saying his prayer in his grave. (Using translation from Muslim 2375a)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ لَمَّا أُسْرِيَ بِي مَرَرْتُ عَلَى مُوسَى وَهُوَ قَائِمٌ يُصَلِّي فِي قَبْرِهِ عِنْدَ الْكَثِيبِ الْأَحْمَرِ