Ref. No. 901/41-13B
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
It is pre-seminal fluid which comes out during sexual arousal and it is called “Mazi” in Shariah. It is obligatory to do wudhu because of it and the person must wash it off as it is impure. Although Ghusl is not required in this substance.
(وليس في المذي والودي غسل وفيهما الوضوء) (فتح القدیر 1/67) وليس في المذي والودي غسل وفيهما الوضوء " لقوله عليه الصلاة والسلام: " كل فحل يمذي وفيه الوضوء " (الھدایۃ 1/20)
And Allah knows best
Darul Ifta
Darul Uloom Waqf Deoband
