What is the expiation for abortion after an illegitimate pregnancy that lasted one month?

Adultery is a heinous crime and a major sin among the grave transgressions. Sincere repentance is obligatory for this enormous sin, along with remorse for the great offense and negligence of Allah's right. Regarding abortion of the fetus after adultery, even if it is before forty days, the fatwa states that it is not permissible, and there is no expiation for it.