Is it permissible for a Muslim man to examine the urinary canal of his penis and look at it or touch it to confirm that something has come out, or should he suffice with looking at the apparent part of the penis? And what is the ruling if he sees traces of fluid deeply embedded in the canal that have not reached the outer surface, and does that affect the validity of ablution and fasting?

It is not legislated for a man to open the urethral canal and look into it to ensure it is free of urine, as this is a gateway to obsessive whispering (waswasah) and contrary to the ease of the Shari'ah. What is legislated is to wash the head of the penis after urinating and to sprinkle water on the private parts or trousers to cut off obsessive whispering. Inspecting the penis, shaking it, and forcing urine out are innovations, and the hadith (definition) narrated about this is weak. Urine exits naturally and does not require squeezing or pressing. If urine does not exit externally, it has no ruling and does not affect ablution or prayer, nor does it harm fasting.