Manusmriti
सुरा वै मलमन्नानां पाप्मा च मलमुच्यते । तस्माद् ब्राह्मणराजन्यौ वैश्यश्च न सुरां पिबेत् ॥ ९३ ॥
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.
english translation
surA vai malamannAnAM pApmA ca malamucyate । tasmAd brAhmaNarAjanyau vaizyazca na surAM pibet ॥ 93 ॥
hk transliteration by Sanscript