“ And I thought to disclose it to you, saying, “Buy it before those who sit here, and before the elders of my people. If you will redeem it, redeem it. But if you will not redeem it, then tell me, so that I may know, for there is none to redeem it besides you, and I am after you.” And he said, “I will redeem it.”
Boaz then called on the near kinsman, in front of ‘those who sit here, even before the elders of my people', acting as witnesses, to buy the land if he wished to do so, so that it could remain in the family (that is why he was said to ‘redeem it'). If he was not willing to do so then the right passed on to the next nearest kinsman, which in this case was Boaz.
As we have seen the purpose of redemption was so that the land might remain in the family and not go to outsiders, but even more specifically it was in order for it finally to be restored to the near family of its original owners. This would require the maintaining of the name in Israel of the original owner (Ruth 4:10), and that would be the duty of the purchase. So what was being bought in this case was the right of use of the land until it could revert back to its original owners, that is, to a son of the dead man as begotten through the goel (the kinsman redeemer). Thus the redeemer, being a near kinsman, had the responsibility to ensure that the family and name of the original owners survived, and he did it by himself begetting sons through any womenfolk who were left of the original family. The purpose of this was in order to ensure that the name of the original owners survived in Israel, along with their ownership of their land as originally allotted to them by YHWH.
On hearing that the land was available the near kinsman immediately said that he would ‘redeem' it. The rights to land were very valuable, especially land which probably bordered on his own as a near kinsman, and the possibility of obtaining it did not come up very often because of the rigid customs that prevailed. It seemed too good an opportunity to miss. But he had not thought out the consequences, possibly because he was not familiar with the Law, or possibly because he had not connected Ruth with the situation (not how Boaz had spoken of Naomi as the ‘seller'). That would not indicate that the law did not exist, only that people are often very vague as to what exactly the law requires. It will be noted that once it was drawn to his attention (and no doubt confirmed by the listening elders) he yielded to Boaz's arguments.
“I thought to disclose it to you.” Literally, ‘I have said (to myself) I will lay bare (disclose) in your ear', a good example of translator's licence which is common in translating Old Testament Hebrew.