Generally the goddess Kali is offered food containing meat and fish, and therefore Kasyapa Muni strictly forbade his wife (Diti) to take the remnants of such food
SB Canto 6
Never eat leftover food, never eat prasāda offered to the goddess Kālī (Durgā), and do not eat anything contaminated by flesh or fish. Do not eat anything brought or touched by a śūdra nor anything seen by a woman in her menstrual period. Do not drink water by joining your palms.
Generally the goddess Kālī is offered food containing meat and fish, and therefore Kaśyapa Muni strictly forbade his wife to take the remnants of such food. Actually a Vaiṣṇava is not allowed to take any food offered to the demigods. A Vaiṣṇava is always fixed in accepting prasāda offered to Lord Viṣṇu. Through all these instructions, Kaśyapa Muni, in a negative way, instructed his wife Diti how to become a Vaiṣṇavī.