What is the ruling on one who grumbles during prayer due to an odor or a person beside him?

Groaning during prayer invalidates it, according to many scholars, if two letters are uttered, because it is considered speech. Others, however, are of the opinion that it does not invalidate it.

As for sighing, if two letters are uttered, it is considered speech according to the Hanbali school of thought, but Sheikh Taqi al-Din holds that it is not speech.

Abu Hanifa and Muhammad both stated that prayer is invalidated by sighing unconditionally, whereas Abu Yusuf initially believed it was invalidated if the intention was to express weariness, but he later retracted that view.

The most cautious approach for a worshipper who groans is to repeat the prayer.