Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Abu Barzah al-Aslami was a soothsayer who judged among the Jews in the disputes they brought to him, and some people of the Muslims also took their disputes to him. So Allah, the Mighty and Majestic, revealed this verse: "Have you not seen those who claim that they believe in what was revealed to you and what was revealed before you, yet they wish to seek judgement from the Taghut, while they were commanded to reject it" [Surah al-Nisa': 60] up to "We intended nothing but good and reconciliation" [Surah al-Nisa': 62].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11993