The Trikayasutra, the Three Body Sutra:
The Anityatāsūtra, The Sūtra on Impermanence:As the title suggests, this sūtra describes the three bodies of the Buddha. While the Buddha is dwelling on Vulture Peak in Rājgṛha, the Bodhisattva Kṣitigarbha asks whether the Tathāgata has a body, to which the Buddha replies that the Tathāgata has three bodies: a dharmakāya, a saṃbhogakāya, and a nirmāṇakāya. The Buddha goes on to describe what constitutes these three bodies and their associated meaning.
KirtIn this brief sūtra, the Buddha reminds his followers of one of the principal characteristics of saṃsāric existence: the reality of impermanence. The four things cherished most in this world, the Buddha says—namely good health, youth, prosperity, and life—are all impermanent