Is it permissible to pray in a garment that has been afflicted with impurity not exceeding a quarter of its area, and is one sinful for leaving his brother to pray in trousers afflicted with prostatic fluid (madhy) or pre-seminal fluid (wady) based on this rule?

Some jurists have gone to the extent of pardoning light impurities but not heavy ones if they do not exceed a quarter of the garment; this is the opinion of the Hanafis. Madhy (pre-seminal fluid) and Wady (thick white discharge) are considered heavy impurities, and anything exceeding the size of a Dirham [coin] is not pardoned. Prayer is not valid with a garment stained by any of these impurities if the stain exceeds the size of a Dirham, before it is purified. If you know that prayer is not valid in an impure garment and you do not alert the person wearing it, you are sinful because alerting them is obligatory as part of enjoining good and forbidding evil.