‘ And Joshua made peace with them, and made a treaty-covenant with them, to let them live. And the princes of the congregation swore to them.'
Following up the token eating of their food to indicate acceptance (compare Genesis 31:54; Exodus 18:12; Exodus 24:11) a treaty-covenant was drawn up. Peace and non-belligerence was promised. ‘To let them live' indicates the practical effect as described in Joshua 9:24. Once these oaths were made it would not be possible to destroy these people as God had commanded. And the oaths were taken by all the princes of the congregation, the leaders of the whole of Israel. It is noticeable in all this that Joshua does not act as a dictator but in consultation with the elders and princes of Israel. When in battle he was in command, but for day by day affairs of government responsibility was shared.
“The princes of the congregation” is a regular Mosaic expression (Exodus 16:22; Exodus 34:31; Numbers 4:34; Numbers 16:2; Numbers 31:13; Numbers 32:2). Israel was seen as ‘the congregation' because they gathered together as one to worship YHWH. There are no good grounds for not seeing the expression as Mosaic. There was a regular ‘congregation' and there were ‘princes'.