Vaishnava Dharmashastra 48.1

48.1

atha karmabhir ātmakṛtair gurum ātmānaṃ manyetātmārthe prasṛtiyāvakaṃ śrapayet ||

Now if a man feels his conscience charged with some guilty act (such as performing a sacrifice for, or accepting a gift from, unworthy persons, or eating excrements) committed by himself (or if his conscience tells him that he has done more evil than good, or if he thinks himself less pure than others), let him boil a handful of barley-gruel for the sake of his own spiritual welfare.