Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 4
सूत उवाचद्वैपायनसखस्त्वेवं मैत्रेयो भगवांस्तथा ।प्राहेदं विदुरं प्रीत आन्वीक्षिक्यां प्रचोदित: ॥ ४ ॥
sūta uvācadvaipāyana-sakhas tv evaṁmaitreyo bhagavāṁs tathāprāhedaṁ viduraṁ prītaānvīkṣikyāṁ pracoditaḥ
Śrī Sūta Gosvāmī said: The most powerful sage Maitreya was a friend of Vyāsadeva. Being encouraged and pleased by Vidura’s inquiry about transcendental knowledge, Maitreya spoke as follows.
Questions and answers are very satisfactorily dealt with when the inquirer is bona fide and the speaker is also authorized. Here Maitreya is considered a powerful sage, and therefore he is also described as bhagavān. This word can be used not only for the Supreme Personality of Godhead but for anyone who is almost as powerful as the Supreme Lord. Maitreya is addressed as bhagavān because he was spiritually far advanced. He was a personal friend of Dvaipāyana Vyāsadeva, a literary incarnation of the Lord. Maitreya was very pleased with the inquiries of Vidura because they were the inquiries of a bona fide, advanced devotee. Thus Maitreya was encouraged to answer. When there are discourses on transcendental topics between devotees of equal mentality, the questions and answers are very fruitful and encouraging.