Is it permissible for him to prostrate in the middle of the sermon in a prostration of gratitude?
Machine translationRead the Arabic original
The questioner : Is it permissible for him to prostrate in the middle of the sermon?
The Shaykh : Yes, yes.
The questioner : For example, if the imam were to be given good news. Yes, indeed.
The Shaykh : There is nothing wrong with it; that is, if the preacher is delivering the sermon and is given news of the Muslims' victory and he prostrates in the middle of the sermon, there is nothing wrong with it.
The Shaykh : Yes, yes.
The questioner : For example, if the imam were to be given good news. Yes, indeed.
The Shaykh : There is nothing wrong with it; that is, if the preacher is delivering the sermon and is given news of the Muslims' victory and he prostrates in the middle of the sermon, there is nothing wrong with it.
Source
قناة «فضيلة الشيخ محمد بن صالح العثيمين»، 1065 - هل له أن يسجد في أثناء الخطبة سجدة الشكر؟ الكافي في فقه الإمام أحمد بن حنبل - ابن عثيمين — youtube.com
The Arabic text is a machine transcription of the audio recording.