What are the duties of the person who intends to offer a sacrifice? Is it permissible for him to have sexual intercourse with his wife? If he commits adultery during the month of Thul-Hijjah and before he offers the sacrifice, will his sacrifice will be acceptable?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

The person who wants to offer a sacrifice is required not to shave or shorten his hair, and not to clip his nails. There is an authentic Hadeeth on the authority of Umm Salamah that the Prophet, sallallaahu ‘alayhi wa sallam, said, “If the [first] ten days [of Thul-Hijjah] begin and a person of you wants to offer a sacrifice he should not touch his hair (trim it, cut it, or shave it) nor clip his nails.” [Muslim]

Apart from this, it is lawful for the man who intends to offer a sacrifice to have sexual intercourse with his wife, to the best of our knowledge. Avoiding hair removal and nail clipping during the first ten days of Thul-Hijjah by the person who offers a sacrifice was justified as being an imitation of those in the state of Ihraam. An-Nawawi commented on this by saying, “Our companions (of the Shafi’i school of jurisprudence) said that this is faulty, because the person who offers a sacrifice is allowed to have sexual intercourse with his wife, apply perfume, and put on form-fitting clothes and the like, and the pilgrim is required to abstain from all of this.”

On the other hand, adultery is a great major sin and a heinous crime that blackens the face, hardens the heart, and blinds the insight. Therefore, Allaah The Almighty made it equal to polytheism. Allaah said in the Quran (what means): {The fornicator does not marry except a [female] fornicator or polytheist, and none marries her except a fornicator or a polytheist, and that has been made unlawful to the believers.} [Quran 24:3] 

No sin after polytheism and murder is graver than adultery. This sin and crime is graver when it is committed during the sacred months when the rewards for righteous deeds are doubled and the punishment for sins becomes grosser.

This heinous act, however, does not affect the validity and acceptance of the sacrifice. Hence, if such a person offers a sacrifice for the Sake of Allaah, then his sacrifice is valid and the reward for it will be recorded with his good deeds, which may dwindle when compared with this great crime (adultery). However, the person who repents after committing this sin, his repentance removes the sin and thus his sacrifice will be accepted, Allaah Willing, and the reward will not be diminished.