ISB ~ Matthew 5 v33

not swear falsely:Jesus forbids oath swearing for private purposes. Oaths are important, however, in the public sector for the good of society. Judges, doctors, soldiers, politicians, and other professionals swear oaths for public service. Oaths are also sworn to make or renew covenants (cf. Heb 6:13-18). In every context, God’s holy name is invoked to bring divine assistance (blessing) to the upright and divine punishment (curse) to those who violate their oaths. In Jesus’ day, the practice of oath swearing was sometimes mishandled; people would swear private oaths for personal advantage. By invoking something other than God’s name (heaven / earth / Jerusalem; 5:34-35), oaths were taken lightly or even disregarded (23:16-22). Jesus denounces this, teaching that truthfulness and integrity should govern private life. Matthew recounts three episodes where such illicit oaths are sworn for personal purposes (14:7; 26:72, 74; 27:25) (CCC 2153-54).