It is narrated from the previous chain that the Noble Prophet (peace and blessings be upon him) used to teach us not to go ahead of the imam in bowing and prostration, and that when he says the takbeer, you should also say the takbeer; when he prostrates, you should also prostrate; when he says "ghayril maghdubi 'alayhim wa la-d-dallin," you should say "Ameen," because if a person's "Ameen" coincides with that of the angels, then by its blessing, all the people present in the mosque are forgiven. And when he says "Sami' Allahu liman hamidah," you should say "Rabbana lakal hamd."