Does the one who joins the prayer begin with the opening supplication if he catches the imam in prostration?

Question:
Honorable Shaykh, may Allah grant you success. This questioner says: If a ma'mum enters the mosque and the imam is in prostration, and he says the takbir of ihram, does he recite the opening supplication, or does he go directly into prostration with the imam?

Answer:
He goes directly into prostration. The opening supplication is a recommended practice (sunnah), not an obligation. Yes.