R. Shimon says: This was not his intent, but what he said was "I will go to my land and to my kindred," and I will convert the people of my land and of my family. Lest you say he went and did not do so, it is written (I Chronicles 2:55) "and the families of scribes who dwelt at Ya'abetz … These were the Kenites who descended from Chammath, the father of the house of Rechav." And thus is it written (Judges 1:16) "And the children of the Kenite, the father-in-law of Moses, ascended from the city of date palms" (Jericho.)
They left a place of fruit, food, and drink, and went to the south of Arad to the desert to learn Torah with Ya'abetz. Who was Ya'abetz? Athniel ben Kenaz. And thus is it written (II Samuel 24:24) "And David bought (on the future site of the Temple) the threshing floor and the cattle for fifty silver shekels."
And elsewhere it is written (I Chronicles 21:25) "And David gave Ornan for the place golden shekels, six hundred." It cannot mean (literally,) golden shekels, for it is written "silver shekels." And it cannot mean silver shekels, for it is written "golden shekels." It must mean, then, that he weighed in gold and bought in silver.
And it cannot mean fifty, for it is written six hundred. And it cannot mean six hundred, for it is written fifty. It must mean, then, that when David saw the place where it was fitting to build the Temple, he collected fifty shekalim from each tribe; all together, six hundred shekalim.