Is it permissible to ask the Imam a question while he is on the pulpit, after seeking his permission?

It is permissible to ask the Imam questions after he ascends the minbar or during the sermon, because the Companions did so with the Prophet, may Allah bless him and grant him peace, and he did not rebuke them. Also, Ibn Qudamah stated the permissibility of this for one who asks the Imam out of need or concerning a matter.