What is the ruling on the tubal ligation surgery that was performed due to severe anemia, and how can one atone for this sin?

Abortion is absolutely impermissible unless it poses a danger to the mother's life or causes her unbearable harm. Temporarily suspending pregnancy for a valid reason, however, is permissible. The expiation for an abortion that occurred without a Shar'i (Islamic legal) justification is sincere repentance, seeking forgiveness, and increasing good deeds and supererogatory acts of worship.