SB 1.9.28

dharmārtha-kāma-mokṣāṁś ca
 sahopāyān yathā mune
nānākhyānetihāseṣu
 varṇayām āsa tattvavit
Word for word: 
dharma — occupational duties; artha — economic development; kāma — fulfillment of desires; mokṣān — ultimate salvation; ca — and; saha — along with; upāyān — means; yathā — as it is; mune — O sage; nānā — various; ākhyāna — by recitation of historical narrations; itihāseṣu — in the histories; varṇayām āsa — described; tattva-vit — one who knows the truth.
Translation: 
Then he described the occupational duties of different orders and statuses of life, citing instances from history, for he was himself well acquainted with the truth.
Purport: 

Incidents mentioned in the Vedic literatures such as the Purāṇas, Mahābhārata and Rāmāyaṇa are factual historical narrations that took place sometime in the past, although not in any chronological order. Such historical facts, being instructive for ordinary men, were assorted without chronological reference. Besides that, they happen on different planets, nay, in different universes, and thus the description of the narrations is sometimes measured by three dimensions. We are simply concerned with the instructive lessons of such incidents, even though they are not in order by our limited range of understanding. Bhīṣmadeva described such narrations before Mahārāja Yudhiṣṭhira in reply to his different questions.