What is the ruling on the congregants' prayer behind an imam who speaks during the prayer? And does only the imam's prayer become invalid, or do the congregants' prayers become invalid along with his? And to what extent is the congregants' prayer connected to the imam's prayer? And what is the meaning of speaking for the benefit of the prayer, and does it invalidate it?

The question contains three issues:

1. The ruling on one who speaks during prayer: Intentional speech not for the sake of correcting the prayer: This invalidates the prayer by consensus and the speaker is considered sinful, requiring him to repeat the prayer. If the Imam is the one who spoke, the prayer of the congregants is invalidated if they knew his prayer was invalid. However, if they did not know (e.g., they did not hear his speech), their prayer is valid. Speech out of forgetfulness or ignorance: This does not invalidate the prayer according to the soundest opinion.

2. The connection of the congregant's prayer to the Imam's prayer: Ibn Taymiyyah chose that the congregant's prayer is connected to the Imam's prayer in some cases but not others, and this is the most moderate opinion. If the Imam makes a mistake in his prayer (such as believing he is in a state of purity when he is not, or omitting some obligatory parts of the prayer due to a mistaken interpretation), his mistake falls only upon him and does not extend to the prayer of the congregants, and their prayer is valid and sufficient. This is indicated by the Prophet's (peace be upon him) saying: "They pray for you; if they are correct, it is for you and for them, and if they err, it is for you and against them."

3. Speech for the benefit of the prayer: Slight speech, customary in common practice, is permissible for the benefit of the prayer, such as asking the Imam about the number of rak'ahs he has prayed if he does not understand gestures or tasbeeh, provided that the speech does not exceed what is necessary. If correcting the prayer is possible through gestures or similar means, then speaking at that time invalidates the prayer.