بُلُوغُ الْمَرَامِ
Bulugh al-Maram 299
The Book of Prayer
وَعَنْ اَلْبَرَاءِ بْنِ عَازِبٍ -رَضِيَ اَللَّهُ عَنْهُمَا- قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ إِذَا سَجَدْتَ فَضَعْ كَفَّيْكَ , وَارْفَعْ مِرْفَقَيْكَ } رَوَاهُ مُسْلِمٌ . [1]
Narrated Al-Bara' bin 'Azib (RA): Allah's Messenger (ﷺ) said: "When you prostrate, place the palms of your hands on the ground and raise your elbows." [Reported by Muslim).
Sunnah.com reference: Book 2, Hadith 185