The Lord Himself in His incarnation as the son of Satyavatī [Vyāsadeva] will consider his compilation of the Vedic literature to be very difficult for the less intelligent persons with short life, and thus He will divide the tree of Vedic knowledge into different branches, according to the circumstances of the particular age.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
कालेन मीलितधियामवमृश्य नॄणां स्तोकायुषां स्वनिगमो बत दूरपारः । आविर्हितस्त्वनुयुगं स हि सत्यवत्यां वेदद्रुमं विटपशो विभजिष्यति स्म
kālena mīlitadhiyāmavamṛśya nṝṇāṃ stokāyuṣāṃ svanigamo bata dūrapāraḥ | āvirhitastvanuyugaṃ sa hi satyavatyāṃ vedadrumaṃ viṭapaśo vibhajiṣyati sma
SB 2.7.36