John Calvin Commentary Joshua 9:20

"This we will do to them, and let them live; lest wrath be upon us, because of the oath which we sware unto them." — Joshua 9:20 (ASV)

This we will do to them, etc. Although, according to agreement, they give the Gibeonites their lives, they ratify the whole covenant only in part. For while the Gibeonites were entitled to be made perfectly secure, they are deprived of liberty, which is dearer than life. From this we infer that Joshua and the others had, as in a case of doubt and perplexity, devised a kind of middle course, so as not to make the oath altogether void. The principal object of this device was to appease the multitude: at the same time, while they were indignant at having been imposed upon by the Gibeonites, they punished the fraud, and did not allow impunity to increase their derision.

It was a harsh condition, in this arrangement, that the Gibeonites were not only doomed to servile labors but withdrawn from their homes, to lead a vagrant and wandering life. The office of menial servants imposed on them was no less lowly than laborious, but the worst of all was to hew wood and draw water, wherever God should be pleased to station the ark.