Is the procedure of tubal ligation to prevent pregnancy permissible (halal) or forbidden (haram), knowing that it was done with the husband's consent due to their inability to bear the responsibility of another child, and that the alternative is birth control pills?

Temporarily delaying pregnancy is generally permissible. It is allowed if there is a fear of discord between the spouses, and it must be with the husband's consent. However, if it is for the sake of livelihood and fear of poverty, then it is not permissible, as it involves disrespect towards Allah and a lack of reliance upon Him. The husband must provide for his wife and children, treat his wife kindly, and avoid harming her.