Should a worshiper close or open their eyes during prostration?

The basic principle is that a worshiper should keep their eyes open and not close them unless there is a valid reason. This is because the majority of jurists consider it disliked (makrooh) to close one's eyes during prayer, due to a prophetic prohibition against it. Moreover, it is a cause for sleep and leads to missing the sunnah of looking at the place of prostration.

An exception to this dislike is if closing the eyes leads to the perfection of khushu' (devotion and humility). For instance, if someone fears losing khushu' because of seeing something that distracts their mind, then closing the eyes is permissible at that time and might even be preferable. It becomes obligatory if not doing so leads to committing something forbidden. Some jurists have gone so far as to say that closing the eyes is not disliked at all if no harm is feared, as it gathers khushu' and prevents the mind from wandering.