Majma al-Zawaid — Hadith 2735

Zayd bin Jubayr narrates: Sayyiduna Abdullah bin Umar saw Sayyiduna Umar, and Sayyiduna Umar saw a young man who was praying; he was making his prayer long and drawing it out. He asked, "Who knows this man?" A man said, "I do." Sayyiduna Abdullah bin Umar said: "If I knew this man, I would instruct him to make the ruku' (bowing) and sajdah (prostration) long, for I heard the Prophet (peace and blessings be upon him) say: 'When a servant stands to pray, his sins are brought and placed on his head and his shoulders, and whenever he goes into ruku' or goes into sajdah, those sins fall away.'"
Imam al-Tabarani recorded this narration in al-Mu'jam al-Kabir. Its chain contains a narrator, Abdullah bin Salih, the scribe of al-Layth. Abd al-Malik bin Shu'ayb bin al-Layth said: He is thiqah (trustworthy) and ma'mun (reliable). A group, namely Imam Ahmad and others, declared him da'if (weak). Other hadiths of this kind will come in the discussion of the virtue of prayer, and Allah knows best.