How can a woman verify the descent of one or two drops of urine after performing istinja’ and wudu’, especially if she smells the odor of urine on her underwear, which is wet from the water used for istinja’? Is this a whisper (waswas) or a reality?

It can be inferred from the questions that the questioner suffers from obsessive-compulsive disorder regarding purification. It is recommended, after urinating, to perform istinja (definition)' (washing oneself after relieving oneself) and then to sprinkle water on the private parts or clothing to cut off the waswasah (whispers/obsessive thoughts). Ibn Qudamah mentioned that this is recommended to remove waswasah, and Al-Nawawi agreed with this. These نقل (transmitted texts/statements) indicate that one is not required to pursue delusions and waswasah. Any suspected wetness thereafter is not considered urine, as it could potentially be water from istinja'. The default state is purity until certainty of impurity. Feeling wetness during wudu' (ablution) or prayer does not invalidate wudu' or prayer if this is due to excessive doubt, to the point of becoming like waswasah; in such cases, the preponderant opinion is not to pay attention to it. The cure for these waswasah is to completely ignore them.