Is it obligatory for the congregant to remain in the bowing (ruku') position when the Imam inadvertently rises to complete the recitation of Al-Fatiha after bowing, or should he follow him?

If the Imam rises from Rukoo’ (bowing) to complete Al-Fatiha, and the worshiper (Ma'moom) knows this, then he should not follow him but should wait for him until he returns to Rukoo’. If the worshiper follows him and then the Imam returns to Rukoo’, his standing is not counted, and he should follow him in the rest of the prayer. They should perform the prostration of forgetfulness (Sujood Al-Sahw) with him at the end of the prayer for the extra standing they performed.