“That no man go beyond and defraud his brother in any matter: because that the Lord is the avenger of all such, as we also have forewarned you and testified.”
King James Version (KJV)
4:6 In this matter - By violating his bed. The things forbidden, here are three: fornication, #1Th 4:3|; the passion of desire, or inordinate affection in the married state, #1Th 4:5|; and the breach of the marriage contract.
1Th 4:6 That no [man] go beyond. Beyond the bounds of purity, so as to wrong his brother. In our age, to assail the purity of wife or daughter is counted as a fearful crime against the family. The Lord [is] the avenger. He will punish the adulterer, or libertine.