Does Yellow Discharge Break Wudu?
Question

If yellow discharge from a woman gets on her underwear, should she wash it off, or can she just leave it and make prayer?
Praise be to Allah.If what is meant by the yellow discharge is the maniy (sexual discharge) because it tends to be a yellowish colour in women, then there is a difference of opinion among the scholars as to whether it is pure or not. The more correct view is that it is pure, because of the hadith narrated by Muslim which states that a man stayed the night as a guest at the house of `Aishah, and in the morning he washed his garment. `Aishah said: “It is sufficient, if you can see it, to wash the place where it is, and if you cannot see it, just sprinkle water over it. There was a time when I used to rub the garment of the Messenger of Allah (peace and blessings of Allah be upon him), then he would pray in it.” (Muslim, no. 288)
Al-Nawawi said in Sharh Muslim (3/198):
“Many scholars said that maniy is pure . This was narrated from ‘Ali ibn Abi Talib, Sa’d ibn Abi Waqqas, Ibn ‘Umar, ‘Aishah, Dawud and Ahmad in the more correct of his two views; it is the madhhab of al-Shafi`'i and the scholars of hadith…” (Fath al-Bari, 2/332)
In Fatawa al-Lajnah al-Daimah li’l-Buhuth (5/381) it says: 
“The emission of maniy due to an erotic dream and so on does not make the clothes worn by the person impure even if it gets on them, because maniy is pure. But what is prescribed is to remove whatever gets onto the clothes for the sake of cleanliness and removing dirt.
But if what is meant is the yellow discharge that comes during menstruation and sometimes afterwards, as narrated in the hadith of Umm ‘Atiyah – “We used not to count the yellowish and brownish discharge as anything” (Al-Nasai, 368) – this is one of the things concerning which there is no dispute that it is impure. 
Shaykh Ibn ‘Uthaymin said in al-Fatawa (1/291):
“What is known among the scholars is that everything that comes out of a woman is impure apart from one thing, which is the maniy. The maniy is pure; apart from that every other substance that comes out of the two passages is impure and breaks wudu. On this basis, everything that comes out of a woman is impure and necessitates wudu. This is the conclusion reached following discussions with some of the scholars and consulting references. But I am still not entirely sure, because some women have this moisture all the time, and if it is continuous, then the solution is to do the same as one who suffers from urinary incontinence: she should do wudu for each prayer when the time for it begins, and do that prayer. I also spoke with some doctors and it became clear to me that if this discharge comes from the bladder, it is as we have said; and if it is from the vagina, it is as we have said, she should do wudu, but it is pure and the things it gets onto do not have to be washed.” 
And Allah knows best.