Śrīmad-Bhāgavatam 3.11.12
SB 3.11.12
Open the full passageSanskrit
ayane cāhanī prāhur vatsaro dvādaśa smṛtaḥ saṁvatsara-śataṁ nṟṇāṁ paramāyur nirūpitam
Translation
Two solar movements make one day and night of the demigods, and that combination of day and night is one complete calendar year for the human being. The human being has a duration of life of one hundred years.