"The Messenger of Allah ﷺ said: 'When any one of you stands in prayer, let him not smooth the pebbles, for he is facing Mercy.'" (Using translation from Nasāʾī 1191)
قَالَ رَسُولُ اللهِ ﷺ «إِذَا قَامَ أَحَدُكُمْ فِي الصَّلَاةِ فَلَا يَمْسَحِ الْحَصَى فَإِنَّ الرَّحْمَةَ تُوَاجِهُهُ»