Jeremiah 42:5 in the World English Bible
Then they said to Jeremiah, “May the LORD be a true and faithful witness among us, if we don’t do according to all the word with which the LORD your God sends you to tell us.
Context
4 Then Jeremiah the prophet said unto them, I have heard you; behold, I will pray unto the LORD your God according to your words; and it shall come to pass, that whatsoever thing the LORD shall answer you, I will declare it unto you; I will keep nothing back from you.
5 Then they said to Jeremiah, The LORD be a true and faithful witness between us, if we do not even according to all things for the which the LORD thy God shall send thee to us.
6 Whether it be good, or whether it be evil, we will obey the voice of the LORD our God, to whom we send thee; that it may be well with us, when we obey the voice of the LORD our God.