Following are a number of back-translations as well as a sample translation for translators of Joshua 9:18:

• Kupsabiny: “The people of Israel did not fight those cities because the leaders of Israel had sworn in the name of God that they would do nothing to them. But all the people of Israel grumbled against the leaders in relation to this matter.” (Source: Kupsabiny Back Translation)
• Newari: “But the Israelites did not slaughter them, for the leaders of the assembly of Israel had sworn an oath in the name of the LORD the God of Israel.
  Having gotten this report whole assembly grumbled with the leaders.” (Source: Newari Back Translation)
• Hiligaynon: “But the Israelinhon did- not -attack them because the leaders/[lit. heads] of the Israelinhon had- already -sworn an oath with them in the name of the LORD, the God of Israel.
  The whole people/community complained against their leaders,” (Source: Hiligaynon Back Translation)
• English: “But the Israelis did not attack the people of those cities, because they had promised to live peacefully with them, and Yahweh had heard them promise to do that.
  All the Israeli people grumbled against their leaders for doing that.” (Source: Translation for Translators)