The Long Āgama Sūtra 6.6

6.6

「時，堅固念王即命太子而告之曰：『卿為知不？吾曾從先宿耆舊所聞，若轉輪聖王金輪離本處者，王壽未幾。吾今已受人中福樂，當更方便遷受天福，今欲剃除鬚髮，服三法衣，出家為道，以四天下委付於汝，宜自勉力，存恤民物。』是時，太子受王教已，時，堅固念王即剃除鬚髮，服三法衣，出家修道。

“King Dṛdhasamādāna then summoned the crown prince and told him, ‘Did you know? I’ve heard from the elders of the past that if a noble wheel-turning king’s golden wheel departs from its place, the king’s life won’t last much longer. Now, I’ve experienced the pleasures of merit among humans, and I’ll pursue the way to experience the merits of heaven. I’m going to cut off my hair and beard, put on the three Dharma robes, and leave home for the path. I will bequeath the four continents under heaven to you. You should apply yourself to caring for its people.’

“The crown prince accepted the king’s instruction, and King Dṛdhasamādāna then cut off his hair, put on the three Dharma robes, and left home to cultivate the path.