Is it permissible for the Imam to prostrate in thanks to Allah on the minbar after mentioning one of the gates of mercy, and is it obligatory for the congregants to follow him in that?

The Friday Khateeb should not descend from the minbar for the prostration of gratitude (sujud al-shukr), nor should he interrupt the sermon to perform it, for several reasons:

Firstly: The prostration of gratitude is recommended upon receiving a new and sudden blessing, not for permanent or recurring blessings. Therefore, the preacher's discourse on God's general blessings does not necessitate the prostration of gratitude.

Secondly: It has not been reported that the Prophet, peace and blessings be upon him, performed the prostration of gratitude on the minbar, even though he experienced recurring blessings in situations that would have called for it. The absence of such a report suggests a preference against it. Moreover, this action is closer to innovation and seeking fame than to the Sunnah and humility.