Is it permissible to stop feeding a cat that has been fed for a month after its kittens have grown up, and is what was done with the flea-infested kittens—returning them to the neighborhood after attempting to care for them—a correct action, or does it incur sin?

May Allah reward you for feeding the cats, as it is a good deed and earns reward, for the Prophet, peace and blessings be upon him, said: "There is a reward for every living being." However, you are not obligated to feed them, and there is no sin upon you for not doing so, as long as you have not confined them. The sin lies only in confining an animal and then not feeding it, for the Prophet, peace and blessings be upon him, said: "A woman entered Hellfire because of a cat she tied up; she neither fed it nor let it eat from the vermin of the earth."