Bhagavatapurana 3.20.2

3.20.2

kṣattā mahā-bhāgavataḥ kṛṣṇasyaikāntikaḥ suhṛt /
yas tatyājāgrajaṃ kṛṣṇe sāpatyam aghavān iti //

2. Vidura who was the great Bhakta of Sri Krishna and His absolutely sincere (unswerving) friend, and who abandoned his elder brother along with his sons for the reason that he was unrighteous (in his conduct towards Krishna *i.e.* in having disregarded Sri Krishna's counsel.)