Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Samurah bin Jundub (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "When you stand to perform prayer (following an imam), do not precede the imam in bowing and prostrating; rather, he will precede you."

It is narrated from Sayyiduna Abu Musa (may Allah be pleased with him), he says: The Messenger of Allah (peace and blessings of Allah be upon him) said: "My body has become heavy, so you should bow (ruku) when I bow, and prostrate (sajdah) when I prostrate, and let it never happen that anyone precedes me in bowing or prostration."

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) taught us the prayer and said: "Do not precede the imam in bowing and prostrating. When he says «الله اكبر», then you say «الله اكبر»; when he says «ولا الضالين», then you say 'Ameen,' for whoever's 'Ameen' coincides with the 'Ameen' of the angels, his previous sins will be forgiven. When the imam bows, then you bow; when he says «سمع الله لمن حمده», then you say «اللهم ربنا ولك الحمد» and do not raise your head before him, and (likewise) when he prostrates, then you prostrate."