John Gill 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)

And, the Gibeonites said unto him
In reply to his motion:

we will have no silver nor gold of Saul, nor of his house ;
this shall not be the ransom or atonement; it was not silver and gold Saul took from them, but the lives of their brethren, and therefore they insist upon life for life:

neither for us shall you kill any man in Israel ;
who were not of the house of Saul; they did not desire any man should die, but who were of that family by whom they had suffered:

and he said, what you shall say, [that] will I do for you ;
whether by inflicting pecuniary fines, or punishing with death, which latter seems to be what they suggested, and afterwards insisted on; whatever, according to law and justice, was required, he was ready to do it for them.