What is the ruling of Islamic law regarding dealing with the problem of urine drops exiting after urination, and what is its impact on the validity of ablution and prayer? And is sprinkling water on the trousers after urinating a correct solution, or does it increase obsessive doubts?

Worship is built upon ease and the removal of hardship. In istinja', it is sufficient to cleanse the outlet of urine after its cessation, without the added burden of trying to expel what is imagined to be inside the penis. It is advisable to sprinkle water on the area and on the trousers after istinja' to ward off waswas (whispers/obsessive thoughts); this is commendable and dispels the waswas. Ignoring waswas is the beneficial remedy for them, for whoever listens to them will find them increasing until they drive him to the point of madness. However, if the emission of urine is continuous and certain, then it is urinary incontinence (salas al-bawl), which has its own specific rulings.