The first part of the body that should reach the ground when a person prostrates
أَخْبَرَنَا الْحُسَيْنُ بْنُ عِيسَى الْقُومَسِيُّ الْبَسْطَامِيُّ، قَالَ حَدَّثَنَا يَزِيدُ، - وَهُوَ ابْنُ هَارُونَ - قَالَ أَنْبَأَنَا شَرِيكٌ، عَنْ عَاصِمِ بْنِ كُلَيْبٍ، عَنْ أَبِيهِ، عَنْ وَائِلِ بْنِ حُجْرٍ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم إِذَا سَجَدَ وَضَعَ رُكْبَتَيْهِ قَبْلَ يَدَيْهِ وَإِذَا نَهَضَ رَفَعَ يَدَيْهِ قَبْلَ رُكْبَتَيْهِ .
It was narrated that Wa'il bin Hujr said: "I saw the Messenger of Allah (ﷺ) when he prostrated, he lowered his knees before his hands, and when he came up he raised his hands before his knees."