The oath is the invoking of a curse upon one's self if one has not spoken the truth (Matthew 26:74 ), or if one fails to keep a promise (1 Samuel 19:6; 1 Samuel 20:17; 2 Samuel 15:21; 2 Samuel 19:23 ). It played a very important part, not only in lawsuits (Exodus 22:11; Leviticus 6:3 , Leviticus 6:5 ) and state affairs (Ant. , XV, x, 4), but also in the dealings of everyday life (Genesis 24:37; Genesis 50:5; Judges 21:5; 1 Kings 18:10; Ezra 10:5 ). The Mosaic laws concerning oaths were not meant to limit the widespread custom of making oaths, so much as to impress upon the people the sacredness of an oath, forbidding on the one hand swearing falsely (Exodus 20:7; Leviticus 19:12; Zechariah 8:17 , etc.), and on the other swearing by false gods, which latter was considered to be a very dark sin (Jeremiah 12:16; Amos 8:14 ). In the Law only two kinds of false swearing are mentioned: false swearing of a witness, and false asseveration upon oath regarding a thing found or received (Leviticus 5:1; Leviticus 6:2 ff; compare Proverbs 29:24 ). Both required a sin offering (Leviticus 5:1 ff). The Talmud gives additional rules, and lays down certain punishments for false swearing; in the case of a thing found it states what the false swearer must pay (
Swearing in the name of the Lord (Genesis 14:22; Deuteronomy 6:13; Judges 21:7; Rth 1:17, etc.) was a sign of loyalty to Him (Deuteronomy 10:20; Isaiah 48:11; Jeremiah 12:16 ). We know from Scripture (see above) that swearing by false gods was frequent, and we learn also from the newly discovered Elephantine papyrus that the people not only swore by Jahu (= Yahweh) or by the Lord of Heaven, but also among a certain class of other gods, e.g. by Herem-Bethel, and by Isum. In ordinary intercourse it was customary to swear by the life of the person addressed (1 Samuel 1:26; 1 Samuel 20:3; 2 Kings 2:2 ); by the life of the king (1 Samuel 17:55; 1 Samuel 25:26; 2 Samuel 11:11 ); by one's own head (Matthew 5:36 ); by the earth (Matthew 5:35 ); by the heaven (Matthew 5:34; Matthew 23:22 ); by the angels (BJ , II, xvi, 4); by the temple (Matthew 23:16 ), and by different parts of it (Matthew 23:16 ); by Jerusalem (Matthew 5:35; compare
Not much is told us as to the ceremonies observed in taking an oath. In patriarchal times he who took the oath put his hand under the thigh of him to whom the oath was taken (Genesis 24:2; Genesis 47:29 ). The most usual form was to hold up the hand to heaven (Genesis 14:22; Exodus 6:8; Deuteronomy 32:40; Ezekiel 20:5 ). The wife suspected of unfaithfulness, when brought before the priest, had to answer "Amen, Amen" to his adjuration, and this was considered to be an oath on her part (Numbers 5:22 ). The usual formula of an oath was either: "God is witness betwixt me and thee" (Genesis 31:50 ), or more commonly: "As Yahweh (or God) liveth" (Judges 8:19; Rth 3:13; 2 Samuel 2:27; Jeremiah 38:16 ); or "Yahweh be a true and faithful witness amongst us" (Jeremiah 42:5 ). Usually the penalty invoked by the oath was only suggested: "Yahweh (or God) do so to me" (Rth 1:17; 2 Samuel 3:9 , 2 Samuel 3:35; 1 Kings 2:23; 2 Kings 6:31 ); in some cases the punishment was expressly mentioned (Jeremiah 29:22 ). Nowack suggests that in general the punishment was not expressly mentioned because of a superstitious fear that the person swearing, although speaking the truth, might draw upon himself some of the punishment by merely mentioning it.
Philo expresses the desire (ii. 194) that the practice of swearing should be discontinued, and the Essenes used no oaths (
That oaths are permissible to Christians is shown by the example of our Lord (Matthew 26:63 f), and of Paul ( 2 Corinthians 1:23; Galatians 1:20 ) and even of God Himself (Hebrews 6:13-18 ). Consequently when Christ said, "Swear not at all" (Matthew 5:34 ), He was laying down the principle that the Christian must not have two standards of truth, but that his ordinary speech must be as sacredly true as his oath. In the kingdom of God, where that principle holds sway, oaths become unnecessary.