Joshua 9:19
But all the princes said unto all the congregation, We have sworn unto them by the LORD God of Israel: now therefore we may not touch them. But all the princes said unto all the congregation, We have sworn unto them by the LORD God of Israel: now therefore we may not touch them.
The princes refused to break the treaty and would not let the congregation touch, strike, or harm the Gibeonites, because they had sworn to them by the Lord God of Israel. That oath remained binding even though it had been obtained by deception. It was binding because keeping it did not require Israel to commit sin or to do wrong. Keeping it involved no sin because the Gibeonites had pledged to renounce idolatry and to worship Jehovah.
A pledged word must be honored even at a cost, and a promise that does not bind a person to do wrong must be kept. Gain, revenge, or self-interest cannot make an oath or pledge disposable. The Gibeonites renounced heathenism, joined Israel, and shared in the blessings of the covenant.