What is the ruling on an act of worship that is affected by showing off (riya') while being performed, such as lowering one's voice in prayer, not for the sake of Allah, but out of fear of people's censure or their negative assumptions?

If showing off (riya') is embedded in the very foundation of an action, the action becomes void and nullified, as Allah Almighty says: "I am the One Who is most independent of partners. Whoever performs an action in which he associates another with Me, I will abandon him and his shirk (association)."

However, if the origin of the action was for Allah, and then the intention of riya' occurred, if it was a fleeting thought that was repelled, it does not harm the action. But if one indulged in it, there is a difference of opinion among scholars. The more probable view is that his action is not invalidated by this, and he will be rewarded according to his initial intention.

Ibn Jarir mentioned that this difference of opinion applies to structured acts of worship, like prayer. As for unstructured acts, like recitation (qira'ah) and remembrance (dhikr), they are interrupted by the sudden intention of riya'.

Lowering the voice in prayer is not riya', but rather it is legislated in Islam. The person afflicted with obsessive thoughts (waswas) should follow the Sunnah and abandon these whispers.