tsaleḥ

This is the older, concrete sense of the word, and it is physical before it is anything else. The picture is of pressing through a barrier: forcing a crossing, bursting out like fire, driving forward with a force nothing can hold back.

The most famous use is when the spirit of the LORD comes upon a person. The verb does not say the spirit helped them or made them successful. It says the spirit rushed onto them, the way a wave or a predator lands on its target, and they were suddenly able to do something far beyond themselves. Samson tears a lion apart, Saul is seized with fury, David is marked out from that day on. The word describes how the power arrives, all at once and from outside, not whether the result was good. The same word is used when an evil spirit rushes on Saul, which is the clearest proof that it names the manner of the onset and carries no built-in approval.

Elsewhere the same forceful motion shows up without a spirit: men ford a river straight across, judgment breaks out like an unquenchable fire, a king rides out to battle. Underneath all of these is one idea, the idea of cutting through.

This is the sense that dominates the word's appearances, and it grew out of the first. If the concrete idea is forcing a way through, the figurative idea is making it all the way through to a good end: a journey that reaches its goal, a plan that comes off, a life that flourishes, a word that accomplishes what it was sent to do.

The word is not about getting rich. From Joseph thriving while a slave and a prisoner, to the tree of the faithful person in Psalm 1, to the suffering servant of Isaiah, what prospers is the fitness of action and result, the sense that a thing has come out right. Israel's writers tie this closely to God being present: when God is with a person, what they do prospers, even in hostile or hopeless circumstances. Genesis says it of Joseph, Joshua ties it to keeping God's instruction, and the later books of Chronicles, Ezra, Nehemiah, and Daniel make it almost a slogan for divine reward.

But the word cuts both ways. The wicked also prosper, and that is exactly the scandal: Jeremiah complains that the way of the wicked succeeds, and Daniel says even a tyrant prospers, but only until the appointed end. Used this way the word is morally neutral. It simply reports that something worked out, leaving open whether God approved of it. A close cousin of this sense is the plain idea of being of use: a ruined cloth or a charred branch that is "good for nothing," that is, succeeds at no purpose at all.