What should be done upon realizing that the Imam is in a state of bowing (ruku'), then noticing a significant distance between the worshipper and the row after the Imam has risen from bowing?

The opinion that bowing (ruku') without being in the row is in accordance with the Sunnah is held by some scholars, who base it on the actions of some Companions. However, the apparent meaning of the hadith of Abu Bakrah indicates that the Sunnah is for the worshipper not to bow until he stands in the row. Abu Bakrah was forbidden from repeating his action, and he was instructed to walk with tranquility until he reached the row. The principle is that whoever comes to the prayer should not bow without being in the row until he takes his place. If someone does this out of ignorance or acting upon the opinion of those who deem it desirable, he is told: "May Allah increase your eagerness, but do not do it again." If the Imam raises his head (from ruku') and you have not yet reached the row, do not interrupt your prayer; rather, walk to the row with unhurried steps. The rak'ah is counted for you according to the majority of scholars. The Shafi'is hold that repeating the prayer for someone who prayed alone behind the row is desirable but not obligatory. As for the Hanbalis, they consider the prayer of one who knew of the prohibition to be invalid, and the prayer of the ignorant person to be valid. Another narration from Ahmad validates the prayer of both, and this is the position of the majority. If the Imam raises his head before you reach the row, then raise your head with him, and then enter the row, taking care not to take many consecutive steps. If you interrupt your prayer and say another opening takbir, the first rak'ah becomes invalid, and you must make up that rak'ah after the prayer. If you do not make it up, you must repeat the entire prayer.