Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.056B.

A muhrim who wears a sewn garment or uses perfume by mistake or through forgetfulness or ignorance of their inadmissibility incurs no penalty.

Ya’la bin Umayyah reported that a man came to the Prophet (peace be upon him) while he was at Al-Ji ranah. The man was wearing a cloak and both his head and beard were dyed and perfumed. He said: “O Allah’s Messenger! I declared my intention for an ‘Umrah, but I did what you see!” The Prophet (peace be upon him) said to him: “Wash your hair and beard, and take off your cloak, and do in your ‘Umrah what you should do in your Hajj.” (Reported by the Group except Ibn Majah)

Bukhari reported that ‘Ata said: “If a muhrim uses perfume or wears sewn clothes, forgetfully or unknowingly, he incurs no penalty, nor is he required to make any atonement.” This is different however, from the case of killing a game – unknowingly or forgetfully – for which a muhrim must slaughter a sheep in compensation, because it involves a monetary guarantee. In matters relating to security of property, knowledge and ignorance, forgetfulness and intention, are all the same, as it is in the cases of guarantee pertaining to people’ s property.