Is it permissible to repeat a prayer if the worshiper made a mistake in it and its ruling was not clear to him, in order to avoid doubts, especially if there is no one among the people of knowledge available to ask at the time of the prayer?

It is out of piety and caution in religious matters to repeat a prayer whose validity is doubted, based on the Prophet's (peace be upon him) saying: "Leave what makes you doubt for what does not make you doubt." A Muslim must also learn the rulings concerning individual obligations, such as prayer, for the Prophet (peace be upon him) said: "Whomever Allah wills good for, He grants him understanding in religion," and "Seeking knowledge is an obligation upon every Muslim."