Sunan an-Nasa'i 1313

Qutaybah informed us; he said: Al-Layth narrated to us, from Ibn ‘Ajlan, from ‘Ali—namely, Ibn Yahya—from his father, from an uncle of his who had fought at Badr, who told him: A man entered the mosque and prayed while the Messenger of Allah (peace and blessings be upon him) watched him, though we were unaware. When he finished, he came over and greeted the Messenger of Allah (peace and blessings be upon him). He said, “Go back and pray, for you have not prayed.” The man went back and prayed, then came to the Messenger of Allah (peace and blessings be upon him), who said, “Go back and pray, for you have not prayed”—twice or three times. The man said to him, “By the One who honored you, O Messenger of Allah, I have exerted myself; teach me.” He said: “When you get up intending to pray, perform ablution and do it well. Then face the Qiblah and say the takbir. Then recite, then bow, being at ease in your bowing. Then rise until you are standing upright. Then prostrate, being at ease in your prostration. Then rise until you are at ease sitting. Then prostrate, being at ease in your prostration. Then rise, and do that in this manner until you have finished your prayer.”