Joshua 9:20
This we will do to them; we will even let them live, lest wrath be upon us, because of the oath which we sware unto them. This we will do to them; we will even let them live, lest wrath be upon us, because of the oath which we sware unto them.
Israel's leaders decided to let the Gibeonites live and spare them because of the oath which they had sworn to them. They would not break their sworn promise even though the treaty had been secured by deception. The Gibeonites had renounced their heathenism and idolatry and joined Israel, sharing in the blessings of God's covenant. Sparing them therefore did not violate the command to destroy the idolatrous Canaanites, so keeping the oath did not require Israel to sin. A pledge that does not require wrongdoing must be held sacred and kept even at loss, and desire for gain, revenge, or self-interest can never excuse breaking it.