俱舍論記 15.118

15.118

「此得妙行至唯人天有」者，答。龍雖受戒，唯得處中妙行業道，非得律儀。是故律儀唯人、天有，非三惡趣。問：若不得戒，何故為受？解云：令生妙行，得勝果故。故《婆沙》百二十四云「扇搋、半擇迦、無形、二形受近住律儀，得律儀不？答：應言不得。所以者何？彼所依身者志性羸劣非律儀器，亦不能為不律儀器。如鹹鹵田，嘉苗、穢草俱不生長。然應授彼近住律儀，令生妙行，當得勝果。」問：此論何故不說無形？解云：此論不說，略而不論。

Regarding 'This is obtaining sublime conduct ... to ... only humans and devas possess it': this is the reply. Although nāgas receive the precepts, they only obtain an intermediate sublime course of action (karmapatha); they do not obtain restraint. Therefore, restraint exists only among humans and devas, not in the three miserable destinies. Question: If they do not obtain the vows, why are they conferred upon them? The explanation says: In order to cause sublime conduct to arise and obtain superior fruits. Therefore the Mahāvibhāṣā, fascicle 124, states: 'When ṣaṇḍhas, paṇḍakas, the sexless (animitta), and hermaphrodites (ubhayavyañjanaka) receive the upavāsa restraint, do they obtain restraint or not? Answer: It should be said that they do not obtain it. Why? Because the basis of their bodies has a weak and feeble disposition and is not a vessel for restraint, nor can it serve as a vessel for non-restraint. Just as on salty, barren land, neither good sprouts nor harmful weeds grow. However, one should confer the upavāsa restraint on them, to cause sublime conduct to arise, so that they may obtain superior fruits in the future.' Question: Why does this treatise not mention the sexless? The explanation says: This treatise omits them for brevity and does not discuss them.