Paraskaragrihyasutra 3.2.4

3.2.4

prāśanānte saktuśeṣaṃ śūrpe nyupyopaniṣkramaṇaprabhṛtyāmārjanāt \4\

After he has eaten (of the sacrificial food), he throws the remainder of the flour into a basket, (and then follow the same rites that have been stated above) from (the sacrificer's) going out down to their cleaning themselves.