SB 2.10.5

avatārānucaritaṁ
 hareś cāsyānuvartinām
puṁsām īśa-kathāḥ proktā
 nānākhyānopabṛṁhitāḥ
Synonyms: 
avatāra — incarnation of Godhead; anucaritam — activities; hareḥ — of the Personality of Godhead; ca — also; asya — of His; anuvartinām — followers; puṁsām — of the persons; īśa-kathāḥ — the science of God; proktāḥ — is said; nānā — various; ākhyāna — narrations; upabṛṁhitāḥ — described.
Translation: 
The science of God describes the incarnations of the Personality of Godhead and His different activities together with the activities of His great devotees.
Purport: 

During the course of the existence of the cosmic manifestation, the chronology of history is created, recording the activities of the living entities. People in general have a tendency to learn the history and narrations of different men and times, but due to a lack of knowledge in the science of Godhead, they are not apt to study the history of the incarnations of the Personality of Godhead. It should always be remembered that the material creation is created for the salvation of the conditioned souls. The merciful Lord, out of His causeless mercy, descends to various planets in the material world and acts for the salvation of the conditioned souls. That makes the history and narrations worth reading. Śrīmad-Bhāgavatam offers such transcendental topics of the Lord in relationship with great devotees. Therefore the topics of the devotees and the Lord are to be given respectful aural reception.