肇論新疏 3.77

3.77

三明，即知三世生死之智，在心明內、鑑他為外。僧那梵音，此云弘誓。難者謂生死界，以如來初心結誓盡度生界，故成佛已酬願利生。

The 'three clarities' are the wisdom knowing birth and death across the three periods of time; being in the mind, they illuminate within, while observing others is without. Saṃnāha is a Sanskrit sound, translated here as the great vow. 'Rescue' refers to the realm of birth and death; because the Tathāgata made a vow at his initial resolve to completely deliver the realm of sentient beings, after attaining Buddhahood he fulfills his vow to benefit beings.