Answered by Mufti Mohammed Tosir Miah
Asalamualaikum, can I use the same soap (clothes washing soap) for washing both clean clothes and those stained with menstrual blood? Can I use one side of the same soap for washing clean clothes and the other side for menstrual blood stained clothes?
There is a principle in Islamic jurisprudence which is:
“Certainty is not lifted by a doubt.” (Al Ashbah Wan Nadhair p.60)
Therefore, with regards to your question, unless you can clearly and visibly see some blood or impurity on the soap, you should presume it to be pure and clean; thus, the subsequent clothes would be considered pure. However, if there was traces of blood then it will make the clothes which you subsequently washed impure.
Sometimes these little doubts can lead to waswasas or Satanic whispers which leads one to have doubts about everything regarding salah, cleanliness and even issues regarding divorce.
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham
This answer was collected from DarulIftaBirmingham.co.uk, which is run under the supervision of Mufti Mohammed Tosir Miah from the United Kingdom.