To diminish the burden of the earth, the unborn Lord will take birth in the Yadu dynasty and perform feats impossible even for the demigods. Propounding speculative philosophy, the Lord, as Buddha, will bewilder the unworthy performers of Vedic sacrifices. And as Kalki the Lord will kill all the low-class men posing as rulers at the end of the Age of Kali.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
भूमेर्भरावतरणाय यदुष्वजन्मा जातः करिष्यति सुरैरपि दुष्कराणि । वादैर्विमोहयति यज्ञकृतोऽतदर्हान् शूद्रान् कलौ क्षितिभुजो न्यहनिष्यदन्ते
bhūmerbharāvataraṇāya yaduṣvajanmā jātaḥ kariṣyati surairapi duṣkarāṇi | vādairvimohayati yajñakṛto'tadarhān śūdrān kalau kṣitibhujo nyahaniṣyadante
SB 11.4.22