What is the ruling on making expiation (Fidyah) for shaving the head due to harm while in the state of Ihram?

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A person permitted to shave their head due to harm while in Ihram has the choice to offer the expiation (Fidyah) either before or after the shaving. This opinion is established by Ahmad. The evidence cited is the report concerning Al-Husayn ibn Ali, who suffered from a head ailment, and after the situation was pointed out, a sacrifice was made, and then his head was shaved. This is analogous to the expiations for Zihar (pronouncing one's wife as unlawful) and oaths, where the expiation may precede the obligation.