Hadith Q1594
وَالْإِخْبَارِ بِأَنَّ الْإِمَامَ مَا سَبَقَ الْمَأْمُومَ مِنَ الرُّكُوعِ، أَدْرَكَهُ الْمَأْمُومُ بَعْدَ رَفْعِ الْإِمَامِ رَأْسَهُ مِنَ الرُّكُوعِ
And the explanation of the matter that when the follower precedes the imam in going into bowing (ruku‘), the follower will make up for that precedence after the imam raises his head. (That is, the amount of his bowing will become equal to the amount of the imam’s bowing.)
Hadith 1594
Sayyiduna Muawiyah (may Allah be pleased with him) narrates that I heard the Messenger of Allah (peace and blessings be upon him) say: "Indeed, my body has become heavy, so do not go into bowing (ruku) or prostration (sujud) before me. For however much I precede you in bowing, you will catch up with me after I raise my head, and however much I precede you in prostration, you will catch up with me after I raise my head." Imam Abu Bakr (may Allah have mercy on him) says that Janab Makhzumi did not mention these words in Yahya's narration: "however much I precede you in prostration." And in the narration of Janab Yahya bin Hakim, it is stated: "Indeed, I have become heavy-bodied, or I have become weak and aged."