Is it necessary for urine to be expelled from the body during ablution?

It is not obligatory to expel urine from the body before, during, or after ablution. Rather, it is obligatory to perform istinja' (cleansing with water) after urinating or defecating to remove impurity, and then perform ablution. If a person is holding back urine or feces, they must relieve themselves first and then perform ablution, based on the hadith: "There is no prayer in the presence of food, nor while one is resisting the two impurities (urine and feces)." As for the mere presence of urine inside the body, it has no effect, and it is not obligatory to expel it; because impurity within its source has no ruling, and it does not become impure except upon separation.