俱舍論頌疏論本 14.118

14.118

釋曰：遮罪雖多，飲酒過重，謂飲酒者心多放逸，必犯律儀。為護律儀，故遮飲酒。酒無定量，少分亦醉，故佛嚴制，乃至茅端亦不許。飲酒非性罪，佛教遮制不許令飲，違遮得罪，故名遮罪。如殺生等，未制戒時，聖必不犯，故名性罪，性是罪故。又性罪相唯染心行，療病飲酒，不為醉亂，許無染心，故非性罪。

The explanation says: Although prohibited offences (pratiṣiddha-sāvadya) are numerous, the fault of drinking liquor is grave. That is to say, one who drinks liquor has a mind filled with heedlessness and will inevitably violate the disciplines. In order to protect the disciplines, drinking liquor is prohibited. There is no fixed limit to liquor; even a small quantity causes intoxication. Therefore, the Buddha strictly prohibited it, not even permitting as much as [a drop on the] tip of a blade of grass. Drinking liquor is not an intrinsic offence (prakṛti-sāvadya). Because the Buddha’s teaching prohibits it and does not allow one to drink, one incurs guilt by violating the prohibition; hence it is called a prohibited offence. As for killing living beings and the like, even before the precepts were laid down, the noble ones would certainly not transgress; hence these are called intrinsic offences, because by their very nature they are offences. Furthermore, the characteristic of an intrinsic offence is that it is performed exclusively with a defiled mind (saṃkliṣṭacitta); but if one drinks liquor to treat an illness, without intending to become intoxicated and delirious, it is admitted to be without a defiled mind; therefore it is not an intrinsic offence.