عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ وَعَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ كَانَ يُصَلِّي عَلَى رَاحِلَتِهِ فِي التَّطَوُّعِ حَيْثُمَا تَوَجَّهَتْ بِهِ، يُوْمِئُ إِيمَاءً، وَيَجْعَلُ السُّجُودَ أَخْفَضَ مِنَ الرُّكُوعِ
It is narrated from Sayyiduna Abu Sa'id Khudri and Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) used to perform voluntary prayers on his mount. Whichever direction it turned, he (peace and blessings be upon him) would gesture for bowing and prostration, and he would bend lower for prostration than for bowing.