18 But the Israelites did not attack them, because the leaders of the assembly had sworn an oath to them by the LORD, the God of Israel. The whole assembly grumbled against the leaders,

Read Joshua 9:18 Using Other Translations

And the children of Israel smote them not, because the princes of the congregation had sworn unto them by the LORD God of Israel. And all the congregation murmured against the princes.
But the people of Israel did not attack them, because the leaders of the congregation had sworn to them by the LORD, the God of Israel. Then all the congregation murmured against the leaders.
But the Israelites did not attack the towns, for the Israelite leaders had made a vow to them in the name of the LORD, the God of Israel. The people of Israel grumbled against their leaders because of the treaty.