“I bowed (in prayer) beside my father, and I put my hands between my knees. He struck my hand and said: ‘We used to do that, then we were commanded to put them on the knees.’”  

رَكَعْتُ إِلَى جَنْبِ أَبِي فَطَبَّقْتُ فَضَرَبَ يَدِي وَقَالَ قَدْ كُنَّا نَفْعَلُ هَذَا ثُمَّ أُمِرْنَا أَنْ نَرْفَعَ إِلَى الرُّكَبِ  

“The Messenger of Allah ﷺ used to bow with his hands on his knees and his upper arms held away from his sides.”  

كَانَ رَسُولُ اللَّهِ ﷺ يَرْكَعُ فَيَضَعُ يَدَيْهِ عَلَى رُكْبَتَيْهِ وَيُجَافِي بِعَضُدَيْهِ