What is the ruling on urine drops that affect the underwear after urinating, and is ghusl required, and how is the underwear purified, and how should one pray in this situation, and should the prayer be repeated when in doubt about not having washed the affected area, and what are the things forbidden for a Muslim at that time?

A Muslim must be careful to avoid impurity. If impurity stains one's garment, it does not necessitate a full ritual bath (ghusl (definition)); rather, it is required to remove the impurity by washing the affected area until its trace disappears. The purity of the garment is a condition for the validity of prayer (salat). If a worshipper does not keep themselves pure from impurity, their prayer is invalid.

If a person is certain about the location of an impurity, they must wash it. If they have a strong suspicion or are unsure of its exact location, they should make an effort to purify it. A small amount of impurity that is difficult to avoid is excused due to the hardship involved.

Whoever does not realize the impurity until after the prayer, their prayer is valid. And whoever knows about it then forgets it, their prayer is valid. Whoever doubts the presence of impurity while performing prayer should complete it. And whoever doubts the removal of impurity must remove it until they are certain of its purity. The original state of garments is purity unless the presence of impurity on them is confirmed. The presence of impurity on a garment only prevents praying with it; it does not prohibit other actions such as reciting the Quran.