Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.044C.

The Shafi’i school holds that there is no harm if a pilgrim forgot and covered his head or wore a shirt in a state of forgetfulness. ‘Ata said: “There is no blame on such a person, but he should seek forgiveness of Allah.” The Hanafi school says that such a person will have to redeem himself (by offering a sacrifice). There is also disagreement on using perfume by mistake or unknowingly. The Shafi’i school holds: “Ignorance and forgetfulness constitute an excuse enough to remove the need for redemption for doing something forbidden, unless it is something that involves damage such as hunting, shaving, and clipping nails.” This is the correct position according to them. We will deal with it at its proper place.