What is the expiation for a husband who agreed to his wife’s sterilization 24 years ago, claiming that her repeated pregnancies posed a danger to her life, due to his ignorance of the Sharia ruling?

Sterilization is not permissible unless a reliable medical report confirms that pregnancy poses an imminent danger to the mother's life. Whoever undertakes this act out of ignorance of the ruling, and based on a report from a doctor they believed to be trustworthy, bears no sin.