AssalamA'laykum wa rahmatullahi wa barakatuh! I actually I had misunderstood a particular ruling, which is that prayer is valid if a small amount of impurity is one clothes. I thought it applied to all kinds of impurities, including madhiy and mud, and not just blood and pus. So being unaware, I once prayed with a bit of mud on my trousers. And also, the mud has now fallen of and no traces of stain can be seen. Are my previous prayers valid, and can I continue praying in those trousers without further washing? What about scraping of dry impurities without washing them? May Allah bless you and your loved ones in this world and the hereafter!
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Some scholars are of the view that the minor impurity is overlooked generally, among those scholars are the scholars of the Hanafi School.
Al-Babarti said in the book Al-‘Inayah Sharh Al-Hidaya:
“The major impurity like the size of the Dirham or less, such as blood, urine, wine, chicken excrement, and donkey urine – it is permissible to pray with it; however, if it is more it is impermissible.” [End of quote]
As for the mud, the basic principle is its purity, so your Prayer in garments stained with mud is valid, and you do not need to repeat it. Assuming that your garment was stained with street mud, and you made sure of its impurity, if it was minor then it is pardoned for the purpose of avoiding hardship.
Al-Fatawa Al-Kubra of Sheikh Al-Islam Ibn Taymiyyah reads:
“If the impurity of street mud was verified, its minor quantity is pardoned, because it is too hard to be avoided as mentioned by our companions [i.e. the scholars of the Hanbali School]”
As for the dirt, if it is Tahir (pure), or its impurity is suspected, then it is not necessary to wash it or rub it off, and the Prayer is sufficient even if it is on a garment or body. But if the dirt is impure, then it is not sufficient to wipe it off; rather, it must be overwhelmed by water until it is gone, and no trace of it remains.
Allah knows best.