وَعَنْ وَائِلِ بْنِ حُجْرٍ رضى الله عنه
قَالَ: «صَلَّيْتُ مَعَ اَلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَوَضَعَ يَدَهُ اَلْيُمْنَى عَلَى يَدِهِ اَلْيُسْرَى عَلَى صَدْرِهِ» أَخْرَجَهُ اِبْنُ خُزَيْمَةَ 11 صحيح
I prayed with the Prophet (sallallahu alayhi wa sallam) and he put his right hand on his left (and then placed them) on his chest.
Bulugh al-Maram 334, Book 2, The Book of Prayer, Hadith 155. 1 min read