In Their Folly The Nations Have Invaded Israel/Judah And, Being Rejected By God, Have Been Utterly Defeated (Psalms 53:5).
‘There were they in great fear, where no fear was,
For God has scattered the bones of him who encamps against you,
You have put them to shame, because God has rejected them.'
Apart from the first clause this verse is totally different in meaning from Psalms 14:5-6. Clearly it has been adapted to a new situation, an invasion that failed, even though the consonantal text is similar. It is clear that the adapter realised that he was dealing with a sacred text, and changed it as little as possible. In Psalms 14:5 the great fear was that of Israel's enemies. Here it is Israel's fear because of their enemies. But the Psalmist points out that there was no need for that fear, because God was with them. And as a consequence He had scattered the bones of their enemies who had encamped against them.
Because He had rejected them Israel was able to put them to shame, presumably by defeating them in some way. This could refer to Judah's ‘victory' over Sennacherib as described in Isaiah 36-37, with the idea that there had really been nothing to fear because God was with them, although it had certainly seemed at the time that there was something to fear. But the addition of ‘you have put them to shame' militates against this, unless we see it as meaning that they put them to shame by their prayers. For the people had nothing to do, apart from prayer, with the defeat of the Assyrians. It could thus refer to some similar invasion that was thwarted, where there was no real danger because God was with the forces of Israel/Judah. Psalms 53:1-4 are here given as an explanation of why God had rejected their enemies.