無量壽經連義述文贊 3.156

3.156

經曰「大命將終」至「痛不可言」者，述云：此後、釋燒也。命是天地壽三大中之一，故云大。窈窕者，幽冥貌。浩浩者，大水貌。茫茫者，冥昧貌。數者，理數。

The sūtra says: 'When the great life is about to end...' up to 'the pain is beyond words.' The commentary states: Afterwards, this explains the burning. Life is one of the three greats—heaven, earth, and longevity—and therefore it is called 'great.' 'Yaotiao' (窈窕) is the appearance of obscurity and darkness. 'Haohao' (浩浩) is the appearance of vast waters. 'Mangmang' (茫茫) is the appearance of dimness and darkness. 'Shu' (數) means the principle's calculation/destiny.