Chapter 62: Companions of the Prophet
The freed slave of Usama bin Zaid said,"Al-Hajjaj bin Aiman bin Um Aiman and Aiman Ibn
Um Aiman was Usama' s brother from the maternal side, and he was one of
the Ansar. He was seen by Ibn 'Umar not performing his bowing and
prostrations in a perfect manner. So Ibn 'Umar told him to repeat his
prayer.
Sahih al-Bukhari 3736