is it permissible for a person performing Salah to close their eyes when standing or performing Ruku` (bowing) and Sujud (Prostration) with the intention of perfecting Khushu` (the heart being submissively attuned to the act of worship) and not being distracted by his eyes?
Showing Khushu` and submission to Allah in Salah is obligatory on a person performing Salah. It is also an attribute of the sincere believers whom Allah praised as being submissive in their Salah. Furthermore, a servant should focus his eyes on the place of his Sujud (Prostration), except when saying Tashahhud (testification recited in the sitting position in the second/last unit of Prayer), he should look at his index finger [when he points it while reciting Tashahhud]. As for closing his eyes during Salah, it is not recommended and is an undesirable act.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.