Anandakanda 2.8.214

2.8.214

amlavetasadhānyāmlameṣīmūtre tataḥ pacet /
ḍolāyantre caturyāmaṃ śuddhireṣāṃ mahottamā //

and then cook it in amlavetasa, fermented grain wash, and ewe's urine
in a swing apparatus for four yāmas; this purification of theirs is of the highest excellence.