What is the ruling on one who encouraged and financially assisted his married sister in having an abortion because her husband refused the pregnancy? Is the diyah (blood money) for the fetus incumbent upon him? If it is, what is its value and who pays it? What are the consequences for the sister and her husband, knowing that the fetus was one month old?

It is impermissible to abort a fetus after the ensoulment, by scholarly consensus. As for before that, during the first forty days, it is permissible for a valid excuse or benefit. However, the husband's unwillingness to have a pregnancy is not a Sharia-compliant excuse for abortion. Assisting the questioner in the abortion is forbidden, and she must repent to Allah. However, she is not obligated to pay blood money (diyah) or offer expiation (kaffarah) because she was not directly involved, and because at that stage of development, the fetus does not necessitate blood money or expiation. The same applies to her sister and her husband; they must repent, and there is no expiation or blood money upon them.