Is the Fajr prayer considered valid when performed in a garment on which a drop of urine fell after the 'Isha' prayer, or must it be repeated? And is it necessary to change the clothes, or is it sufficient to wipe the spot of urine three times?

If one prays with a ritually impure garment out of forgetfulness, their prayer is valid, and they are not required to repeat it, according to the more correct opinion. However, if they do so intentionally, their prayer is invalid and must be repeated. The purification of urine impurity is achieved by immersing its location with water; wiping is not sufficient. If the impurity is very slight, it may be pardoned by some scholars, and prayer is valid in its presence.