唯有如来应正等觉， 得般涅槃，成就一切功德故；阿罗汉、辟支佛不成就一切功德，言得涅槃者是佛方便。
《胜鬘师子吼一乘大方便方广经》
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Only the Tathagatas, worthy of offerings and perfectly enlightened, attain parinirvana due to their having achieved perfect merits and virtues; arhats and pratyekabuddhas have not perfected all merits and virtues and are said to have attained nirvana only as an expedientsaying by the Buddha.
The Lion’s Roar of Queen Srimala, the single-vehicle great expedience, the corrective and extensive Sutra[Srimaladevi Simhanada Sutra]
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所以说，阿罗汉、辟支佛证无余涅槃，那是佛陀慈悲方便说法来鼓励他们；因为弘法的过程中，必须先有他们能证无余涅槃，为众生作证，众生才会有具足信心，否则无法对佛生起具足的信心。有了具足信心，然后才次第引入般若，让他们安住于佛道之中，才会有渐教次第说法。
《胜鬘经讲记》第二辑，页37
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To say that arhats and pratyekabuddhas have realized there mainderless nirvana is just the Buddha’s encouragement out of compassion and expedients. In the process of spreading the Buddha Dharma, it is necessary to show sentient beings that arhats and pratyekabuddhas can realize the remainderless nirvana in order to elicit their strong faith. Otherwise, they will not develop sufficientfaith in the Buddha. Once their faith is firmly in place,they can subsequently be led into the prajna and abide in
the way to Buddhahood; this is how the Buddha’s gradualteaching in the progressive stages came into being.
A Discourse on the Srimaladevi Simhanada Sutra, Vol. 2, p. 37
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