Jeremiah 42:5
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.
Cross-reference
Jeremiah 43:4 records their immediate disobedience—contrasting sharply with their solemn oath to obey here.
In Jeremiah 5:2, God condemns swearing falsely by His name—this oath sets up the same standard, which the remnant will later fail.
In Genesis 31:50, Laban invokes God as witness between Jacob and himself—the same covenant formula used here for the remnant's oath.
In Deuteronomy 5:27-29, the people make the same promise to obey God through Moses, and God laments their lack of heart.
In Judges 11:10, Jephthah and the elders say 'The Lord be witness between us'—the identical phrase used here for the remnant's promise.
In 1 Samuel 12:5, Samuel calls the Lord as witness against Israel—here the remnant calls Him as witness to their obedience.
In 1 Samuel 20:42, David says 'the Lord is between you and me'—a similar witness formula between parties, here between God and the people.
In Micah 1:2, the Lord is called as a witness against the people—here the remnant invites Him as witness to their oath, a solemn parallel.
In Malachi 2:14, the Lord was witness between a man and his wife—a similar witness role, here between God and the remnant's covenant promise.
Revelation 1:5 calls Jesus the faithful witness—the same title used here for God as witness to their oath.
Revelation 3:14 calls Jesus the faithful and true witness—nearly identical to the 'true and faithful witness' here.
In Exodus 20:7, taking the Lord's name in vain is forbidden—here the people risk exactly that if they break their oath to obey.
In Malachi 3:5, the Lord becomes a swift witness against sinners—here the people call Him as witness, setting up a future witness in judgment.
In Romans 1:9, Paul also calls God as witness to his prayers—a similar appeal to divine witness as here.