Adbhutasagara 48.3

48.3

tacca riṣṭaṃ dvividhaṃ niyatamaniyataṃ ca| tatra kālamṛtyusūcakaṃ niyatam| gaṇitāgatāyuḥ samāptyāmaraṇaṃ kālamṛtyustatra pratīkārābhāvaḥ|
mahābhārate|
na mantro na tapo dānaṃ na mitrāṇi na bāndhavāḥ|
śaknuvanti paritrātuṃ naraṃ kālena pīḍitam||

And that sign of death is twofold: fixed and unfixed. Among these, that which indicates timely death is fixed. Timely death is death upon the expiration of one's calculated lifespan; in that case, there is no remedy.
In the Mahābhārata:
"Neither mantra, nor ascetic practice, nor gift, nor friends, nor kinsmen
are able to protect a man afflicted by Time."