From Rigpa Wiki
Parinirvana (Skt. parinirvāṇa; Wyl. yongs su myang 'das) — 'final nirvana'. The final passing beyond suffering manifested by buddhas and highly realized masters at the end of their lives. Passing into parnirvana is the twelfth of the twelve deeds of a buddha. Shakyamuni Buddha demonstrated passing into parinirvana at the age of eighty in the town of Kushinagara, after saying, "It is in the nature of all things that take form to dissolve again. Strive with your whole being to attain perfection."