If I felt a line of wetness in my underwear when I got high pressure of toilet but the wetness is not having any excreta traces and not the foul smell from the wet part. I am thinking that it is sweat and leave it without washing. So, is it necessary to wash the underwear or not?
بسم الله الرحمن الرحيم
(Fatwa: 715/522/SN=6/1439)
When there is neither any stain nor any bad smell then it is probable that this is sweat as you also think; hence in the question mentioned above, it is not necessary to wash the underwear. Your salah will also be valid if you offer your salah wearing the underwear without washing it.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband