The Biblical passage spanning the details of Amnon and Tamar (and Absalom and David…) is a heart-wrenching story. I have to mentally prepare myself before reading it, to be honest.
As I read through it this time, I paid more attention to a “supporting actor,” as it were: Jonadab. Both Amnon’s friend and cousin (2 Samuel 13:3), he plays a vital role in this narrative.
After noticing that Amnon was sick (which was 100% self-inflicted) and asking about what was wrong, instead of taking note of the incestuous and rape-like thoughts he was experiencing and influencing him away from them, Jonadab gives Amnon a way of acting on such ideas.
And…then he does.
Now, I don’t believe Jonadab was responsible for what Amnon did. After all, he didn’t force him to do anything and Amnon had the desire before Jonadab entered the picture. Still, Jonadab helped Amnon go from temptation to conceiving of sin (James 2:14-15). He is still a guilty party, and a beyond worthless friend.
I had already noticed this part, though. I knew Amnon had a friend who encouraged him to take advantage of his sister. What I hadn’t noticed was the second thing Jonadab did.
Two years passed after Amnon raped his sister, and King David did absolutely nothing as punishment. Absalom, Tamar’s sister, then took it upon himself to take care of things. At a gathering with his brothers, he had his soldiers kill Amnon for what he had done. In the commotion, some messengers got it wrong and told King David that Absalom had killed all of his sons. As he started to mourn the loss of all of his children, Jonadab spoke up, apparently in the throne room at the time.
Jonadab told him, “Let not my lord suppose they have killed all the young men, the king’s sons, for only Amnon is dead. For by the command of Absalom this has been determined from the day that he forced his sister Tamar. Now therefore, let not my lord the king take the thing to his heart, to think that all the king’s sons are dead. For only Amnon is dead.” (2 Samuel 13:32-33)
What Jonadab said was true: only Amnon was killed, so the king didn’t need to mourn all of his sons. What strikes me though is how he said it. Only Amnon is dead. It’s just one son, and it was the bad one, right? So relax. Also, Absalom has been planning this since the day Amnon violated his sister Tamar.

I don’t get why Jonadab did this. What was in it for him? To lead the prince into this grievous sin, and then turn around and say “Of course this is what was going to happen.” He wasn’t going to be promoted to prince, there was no prestige. What was the purpose of such wickedness? Personally, he strikes me as intensely demonic.
When we’re introduced to Jonadab, he’s described as “a very crafty man” (2 Sam. 13:3), which reminds me of how the serpent in the Garden of Eden was noted as being “more cunning than any beast of the field which the Lord God had made” (Genesis 3:1). Jonadab suggests a way for Amnon to act on his sinful desires right away; doesn’t the devil provide such unhelpful suggestions all of the time?
Then, after committing sin, Jonadab turns on him, saying his death was inevitable and it was “only Amnon,” so no need to really grieve, Your Majesty. Does not the devil accuse us to our Father, focusing on all the bad we’ve ever done (Revelation 12:10)?
I’m not even sure where to end that. The importance of having good friends? For sure. I think it also just shows the deceptiveness of sin. Amnon received no lasting pleasure from indulging his wicked desires, and he destroyed multiple lives (including his own) by doing so. It wasn’t worth it. Sin is never worth it. It is only by believing a lie that we can fall for the advice of the Jonadabs of life.