Is it obligatory to repeat the prayers when a small amount of urine exits after Istinja and Istibra? Is it permissible to pay expiation for an oath to the mosque, and what is its value in euros, and is it permissible to pay it to one person?

What exits with urine requires waiting for its cessation, then purifying oneself for prayer. Past prayers, performed with ignorance of a urine drop exiting and then performing ablution afterward, are hoped to be valid, as avoiding impurity is a condition when one has knowledge and ability. The expiation for an oath, according to the majority of scholars, is feeding or clothing ten needy people. It is not permissible to give it to a single needy person or to pay its monetary value. It must be given to the needy, not to the mosque.