Answered by Shaykh Faraz Rabbani
If a woman has a long jilbab and walks while dragging it on the ground and is sure that she passed over najasah etc the excrement of a dog and is also sure that it got to her clothes, is it ok to walk a little bit more and assume that the najasah is clean. Please tell a practical way out.
Walaikum assalam wa rahmatullah,
Unless there are clear signs of filth on her clothes, her clothes are to be considered clean. This was explicitly indicated by the Messenger of Allah (Allah bless him and give him peace), in a hadith related by Imam Tirmidhi in his Sunan.
Contact with dry filth does not render one’s clothing or body filthy unless signs (i.e. color, smell, or taste) of the filth affects them. Note, too, that a small amount of filth (i.e. less than 5 cm in diameter) is excused.
[ref: Imam Shurunbulali, Imdad al-Fattah]
Wassalam,
Faraz Rabbani.