سنن النسائي

It was narrated that Al-Aswad said: "Alqamah and I entered upon 'Abdullah bin Mas'ud and he said to us: 'Have these people prayed?' We said: 'No.' He said: 'Get up and pray.' So we went to stand behind him, and he put one of us on his right and the other on his left, and he prayed with no Adhan and no Iqamah. When he bowed he interlaced his fingers and placed his hands between his knees, and he said: 'I saw the Messenger of Allah (ﷺ) doing that.'"