Answered by Shaykh Amjad Rasheed
Some brothers, may Allah reward them, give a lesson immediately after the prayer without giving the people enough time to perform their sunna prayers .., and during their lesson, they disturb the latecomers who are completing their prayers. Their proof in this is that they want to give the people knowledge before they leave. Is it permissible to reject this? Especially after knowing that some of the scholars of Ahl al-Sunna wa Jama`a have mentioned that doing a good act that conflicts with a sunna act of a specified time is a bid`a? The default should be that one performs the sunna and then does whatever he wishes.
The ruling according to our Shafi’i imams is that it is haram for a Koran reciter to recite out loud if it disturbs someone who is praying or sleeping, for the harm that it entails. So from this, it is taken that it is haram to raise one’s voice to teach a lesson when it disturbs those praying, such as latecomers. If a teacher needs to raise his voice, he may delay until people are finished praying.
As for calling people to learn and make them listen to the lesson before they leave, it is not correct to take this [s. stance]. For whoever does not want to listen to the lesson will turn away from it anyways, no matter whether the teacher stands up immediately after the prayer or a little later. The best thing is that the people be informed after the prayer that a lesson will take place after the they pray their sunna prayers, for example. So whoever wants the good of listening to knowledge, may stay for it, and whoever doesn’t, can leave. It also may be possible that some do want to listen to the knowledge but an obstacle or excuse is in their way at the moment, so they are excused.
As for when there isn’t a person praying that would be disturbed by a loud voice from the teaching, rather there is only someone who is doing his post-prayer dhikr, then I have not seen a text about it from our imams. However, it has been said that the matter of dhikr is lighter than the matter of the prayer, because usually, dhikr is shorter than prayer and dhikr doesn’t have essential pillars that one fears mixing up because of disturbance, while the prayer does. Also, a person making dhikr can sit down on one side of the masjid so that loud voices don’t bother him. So it seems, and Allah knows best, that it is not haram in this case to raise one’s voice in teaching.
– Amjad
(Translated by Shazia Ahmad)