It is narrated from Ikrimah (may Allah have mercy on him): Sayyiduna Ibn Abbas (may Allah be pleased with them both) did not consider there to be any harm in the sweat of a menstruating woman or a person in a state of major ritual impurity (junub).
Hadith Referenceسنن دارمي / من كتاب الطهارة / 1067
Hadith Takhrijاس روایت میں ہشیم مدلس ہیں اور انہوں نے عنعنہ سے روایت کیا ہے، لیکن عبدالرزاق نے [مصنف 1430] میں بسند صحیح ذکر کیا ہے۔
Brief Explanation
(Commentary on Ahadith 1058 to 1067)
From all these narrations, it is established that if sweat from a woman in the state of menstruation (hayd) or from someone in the state of major ritual impurity (janabah) gets onto clothes, the clothes do not become impure. Therefore, there is no harm in praying in such clothes, nor is there any need to wash them. However, if semen (mani) or any other impurity gets onto the clothes, then that spot or the garment should be washed.