The World Federation One Stop Fiqh

Ritual 300

If a pilgrim was unaware of the najasah on his body or clothes, and became aware of it in the course oftawaf, or his body or clothes became najis in the course of tawaf, he should change into clean ones and completetawaf, if tahir clothes were available. If not, and it was known that the najasah occurred after completing the fourth round of tawaf, he should abandon it, clean the clothes or himself, and complete tawaf.

If this occurs before completing the fourth round, he should abandon tawaf, clean the clothes or himself and, as a matter of precaution, perform another complete tawaf, even though it, apparently, is not obligatory to repeat tawaf.