Charles Ellicott Commentary 2 Samuel 21:4

"And the Gibeonites said unto him, It is no matter of silver or gold between us and Saul, or his house; neither is it for us to put any man to death in Israel. And he said, What ye shall say, that will I do for you." — 2 Samuel 21:4 (ASV)

No silver nor gold.—Money compensations for sins of blood were extremely common among all ancient nations, but were expressly forbidden in the Law of Moses (Numbers 35:31), and in this respect the Gibeonites appear to have accepted the teaching of the law of Israel.

Kill any man in Israel. —Although the guilt of Saul’s sin, until it should be expiated, rested upon all Israel, the Gibeonites recognize that he had committed it, and do not seek that, apart from their connection with him, any Israelite should suffer on their account. David appreciates the fairness of their view of the matter, and promises beforehand to do whatever they require.