BG 17.10-12
That which is stale and flat, putrid and corrupt, leavings also and unclean, is the food dear to the dark. The sacrifice which is offered by men without desire for fruit, as enjoined by the ordinances, under the firm belief that sacrifice is a duty, that is pure. The sacrifice offered with a view verily to fruit, and also indeed for self-glorification, O best of the Bhâratas; know thou that to be of passion.