Is standing for the prayer done when one sees the imam, or when the mu'adhdhin says, "The prayer has begun"?

Question:
The Prophet (peace and blessings be upon him) said, "When you see me, stand up," in the hadith. Do we say that the recommended practice (sunnah) for standing for the prayer is when one sees the imam, or when the mu'adhdhin says, "The prayer has begun"?

Answer:
It is correct that it is when one sees the imam. It is correct that standing for the prayer is when one sees the imam, because the imam may be the one to call the iqamah, or the mu'adhdhin may be the one to call it. If one sees the imam but he has not yet come out to the prayer area, then when one sees the imam, he stands up.