Ketzot HaChoshen, Choshen Mishpat 290:3

In my humble opinion, this would appear to answer the question of Tosafot regarding that which is said in the first chapter of Baba Batra (8b) that R. Ammi was compelled [by Rava] to give tzedakah, and yet it is said (Chulin 110b) that any positive commandment whose reward is written next to it, the court may not compel, and all of the Rishonim (early rabbinic legalists) have already been bothered by this. According to what I have said that tzedakah has within it a lien on property to give from it to tzedakah, it is the money of the poor people that you are holding onto, as if you owed them an actual debt. Therefore, we compel a person to return to the poor people that which the person owes them. Regarding this, even though its reward is written next to it, it is certainly incumbent on the court to compel the person to return that which they owe, since their property is mortgaged. [Translation by David Fried. Edited for gender neutrality]