Answer:
(Fatwa: 512/J)
Yes, in this case you can pray in the clothes after having bath and taking off the underwear; since the clothes are clean.
The above reply is in case of sperm, but if the fluid is other than sperm then the ruling may be different.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
