וּלְאַמְנ֣וֹן רֵ֗עַ וּשְׁמוֹ֙ יֽוֹנָדָ֔ב בֶּן־שִׁמְעָ֖ה אֲחִ֣י דָוִ֑ד וְי֣וֹנָדָ֔ב אִ֥ישׁ חָכָ֖ם מְאֹֽד׃
Amnon mempunyai seorang sahabat bernama Yonadab, anak Simea, saudara Daud; dan Yonadab adalah seorang yang sangat cerdik.
Avot DeRabbi Natan
Do not befriend the wicked. This teaches us that a person should not befriend a bad person, nor a wicked person. For so we find with Jehoshafat, that he befriended Ahab and went up with him to Ramot Gilad, and the Eternal’s rage came out upon him. Then he befriended Ahaziah [and they made ships in Etzion Gever, and the Eternal destroyed his work, as it says,] (II Chronicles 20:37), “‘Because you have befriended Ahaziah, the Eternal will destroy your work,’ and so the ships were broken up.” And so, too, we find with Amnon, who befriended Jonadab, who then gave him bad advice, as it says (II Samuel 13:3), “Amnon had a friend named Jonadab, son of David’s brother Shim’ah; and Jonadab was a very wise man” – that is, wise in the ways of wickedness. Another interpretation of Do not befriend the wicked: Even to study Torah.