תּלמוד אויף נחמיה 2:6

(Ezra 6:9) "Whatever is needed--young bulls, rams, male lambs for burnt offerings to the God of heaven, and wheat, salt, wine and oil, as requested by the priests in Jerusalem--must be given them daily without fail" [which shows he was a good king to the Jews]! Rabbi Yitzchak said to him: Rabbi, from your very source [I will prove you are wrong]. (Ezra 6:10) "...so that they may offer sacrifices pleasing to the God of heaven and pray for the well-being of the king and his sons."

Rav Yosef, and some say it was Rabbi Yitzchak, said, How do we know that he turned bad? From here, (Nehemiah 2:6) "And the king said to me, and the 'shegel' was sitting next to him..." What is this 'shegel'? Rabbah bar Leima said in the name of Rav: It is the dog [and it was there for illicit purposes].