Heidelberg Catechism 36.101

Chapter 36 — Lord's Day 36

Section 101. Q. 101: But may we swear an oath in God's name if we do it reverently? A. Yes, when the government demands it, or when necessity requires it, in order to maintain and promote truth and trustworthiness for God's glory and our neighbor's good. Such oaths are approved in God's Word and were rightly used by Old Testament saints.