Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 2
क्षत्ता महाभागवत: कृष्णस्यैकान्तिक: सुहृत् ।यस्तत्याजाग्रजं कृष्णे सापत्यमघवानिति ॥ २ ॥
kṣattā mahā-bhāgavataḥkṛṣṇasyaikāntikaḥ suhṛtyas tatyājāgrajaṁ kṛṣṇesāpatyam aghavān iti
Śaunaka Ṛṣi inquired about Vidura, who was a great devotee and friend of Lord Kṛṣṇa and who gave up the company of his elder brother because the latter, along with his sons, played tricks against the desires of the Lord.
The incident referred to here is that Vidura left the protection of his elder brother Dhṛtarāṣṭra, went traveling everywhere to sacred places and met Maitreya at Hardwar. Śaunaka Ṛṣi here inquires about the topics of the conversation between Maitreya Ṛṣi and Vidura. Vidura’s qualification was that he was not only a friend of the Lord but also a great devotee. When Kṛṣṇa tried to stop the war and mitigate the misunderstanding between the cousin-brothers, they refused to accept His counsel; therefore Kṣattā, or Vidura, was unsatisfied with them, and he left the palace. As a devotee, Vidura showed by example that anywhere that Kṛṣṇa is not honored is a place unfit for human habitation. A devotee may be tolerant regarding his own interests, but he should not be tolerant when there is misbehavior toward the Lord or the Lord’s devotee. Here the word aghavān is very significant, for it indicates that the Kauravas, Dhṛtarāṣṭra’s sons, lost the war because of being sinful in disobeying the instructions of Kṛṣṇa.