Answered by Shaykh Yusuf Weltch
Sometimes when I take my time doing istinja and do it for a while, about 15 mins after, I feel an urge to urinate. But that urge slowly goes away, and I think I may release something, which is why the urge goes away. Is it possible that this is because of trapped istinja water? Does this break wudu?
This mostly happens when I do istinja for a while.
In the Name of Allah, the Most Merciful and Compassionate
The exiting of residual water from istinja does not break the wudu. [Shurunbulali, Maraqi al-Falah]
The Rulings of Islam Are Not Based On Conjecture
It is important to remember that the rulings of purity do not revolve around ‘I think’ or ‘What if’ or ‘Possibly.’
The basis of the removal of filth is a reasonable surety. You do not need to do istinja for 15 minutes. A sound istinja can be done within merely a few seconds of cleaning.
I would advise you to reduce the time it takes you to make istinja significantly. Wash until you are reasonably sure that the impurity is gone.
Once you have reached reasonable surety, never second guess.
Allah Most High says, “…and He has not placed any undue hardship upon you in the religion.” [Quran, 22:78]
Burdening Ourselves More than Necessary
Due to a lack of knowledge and an avidness for caution in religion, many burdens themselves unnecessarily. In actuality, there is no such thing as caution without knowledge.
This false caution leads to very detrimental sicknesses like doubts and misgivings, called waswasa.
What is True Caution?
Proper caution is to follow the Sunna of the Prophet (may Allah bless him and give him peace).
For the one constantly in doubt, abandoning caution is often the best cure.
“As for the one who is often inflicted with misgivings, it is necessary for them to sever the cause of the misgivings and not to give it any consideration. This is because it is the doing of Shaytan, and we have been commanded to oppose him.” [Ibn ‘Abidin, Radd al-Muhtar]
Check this reader on waswasa:
A Reader on OCD and Waswasa (Baseless Misgivings)
The long-term cure for these constant doubts is to seek a deeper understanding of Islamic Knowledge. With knowledge, Shaytan cannot deceive you with his whispers and plots. I would advise you to find authentic scholars in your area and study an introductory text in Islamic Jurisprudence with them.
Please note that SeekersGuidance.org has classes available in Islamic Jurisprudence and many other subjects.
May Allah ease all of you affairs and protect you and us from the plots of Shaytan
Hope this helps
And Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani