Manava Dharmashastra 11.94

11.94

gauḍī paiṣṭī ca mādhvī ca vijñeyā trividhā surā
yathaivaikā tathā sarvā na pātavyā dvijottamaiḥ //

Sura, indeed, is the dirty refuse (mala) of grain, sin also is called dirt (mala); hence a Brahmana, a Kshatriya, and a Vaisya shall not drink Sura.