The Law Code of Devala 2.8: Madanapārijāta · Ācāra · Śūdrakamalākara +2

2.8

bhuktocchiṣṭaṃ samādāya sarvasmāt kiṃcid ācaman | ucchiṣṭabhāgadheyebhyaḥ sodakaṃ nirvaped bhuvi

“Revered sir, how indeed may Brahmins, Kṣatriyas, / Vaiśyas, and Śūdras in order attain purification when carried off by Mlecchas?

Taking a little of every leaving of the meal, before sipping, he should offer it with water on the ground to those whose share is the leavings.