Mishkat al-Masabih 4 Prayer كتاب الصلاة 753

وَعَنْ جَابِرٍ قَالَ: بَعَثَنِي رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي حَاجَةٍ فَجِئْتُ وَهُوَ يُصَلِّي عَلَى رَاحِلَتِهِ نَحْوَ الْمَشْرِقِ وَيَجْعَلُ السُّجُودَ أَخفض من الرُّكُوع. رَوَاهُ أَبُو دَاوُد

Jabir said, “God’s Messenger sent me on some business, and when I came to him he was praying on his riding-beast towards the east and making the prostration lower than the bowing.” Abu Dawud transmitted it.