It is narrated from Hazrat Ata that he heard Sayyiduna Abdullah bin Zubair (may Allah be pleased with him) saying to the people from the pulpit: When any of you enters the mosque while the people are in ruku (bowing), he should go into ruku as soon as he enters, then, while remaining in the state of ruku, he should slowly move forward and join the row. Indeed, this is the Sunnah. Hazrat Ata says that he saw Sayyiduna Abdullah (may Allah be pleased with him) doing this.