Being diligent, he attains perpetual liberation. And it is impossible for that bhikkhu to fall away from that perpetual deliverance.
BB: MA quotes the Patisambhidamagga (ii.40) for as definition of asamayavimokkha (literally "non-temporary" or "perpetual" liberation) as the four paths, four fruits, and Nibbana, and of samayavimokkha (temporary liberation) as the four jhanas and four formless attainments.
See also MN 122
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“Indeed, Ānanda, that a bhikkhu delighting in company, enjoying company, devoted to delight in company, delighting in society, enjoying society, finding satisfaction in society should enter upon and dwell in either the temporary, or the permanent and unshakeable, delectable mind deliverance, that is not possible. But when a bhikkhu lives alone, apart from society, that he may be expected to enter upon and dwell in the temporary, or the permanent and unshakeable, delectable mind deliverance, that is possible.
Ven Sujato notes that the Chinese Agama version of the sutta does not have the line:
- And it is impossible for that bhikkhu to fall away from that perpetual deliverance.
and the known Sarvastivada nikayas do not have this sutta at all.
Whether liberation is permanent or not was a point of disagreement between sects, so this line may be a late addition to the Theravada version.
Mike