A solemn vow or promise to fulfill a pledge.
Two terms in Hebrew mean “oath”:
‘ala
sebu’a
In ancient times, the term meant to enter a solemn, magical bond with the number seven. The ancient connections are now lost. Abraham and Abimelech swore an oath at Beersheba (the well of seven). As proof he dug a well, Abraham set aside seven ewe lambs (Genesis 21:22–31). The former term ‘ala, often translated as “oath,” properly means “curse.” At times, the two terms are used together (Numbers 5:21; Nehemiah 10:29; Daniel 9:11). Any breach of the oath would result in a curse. The Lord said that he had made a covenant and a curse with Israel—that is, breaking the covenant would be followed by a curse (Deuteronomy 29:14 and the following verses).
An oath was taken to confirm an agreement or, in a political situation, to confirm a treaty. In Israel and its neighbors, God (or the gods) guaranteed the agreement. His (or their) name was invoked for this purpose. When Jacob and Laban made an agreement, they erected a heap of stones as a witness (Genesis 31:53). If either party transgressed the terms, it was a heinous sin. One of the Ten Commandments dealt with empty affirmations. It said, "You shall not take the name of the LORD your God in vain, for the LORD will not leave anyone unpunished who takes His name in vain” (Exodus 20:7). The people of Israel were forbidden to swear their oaths by false gods (Jeremiah 12:16; Amos 8:14). To breach an international treaty, where the oath was taken in the Lord’s name, merited death (Ezekiel 17:16–17). It was one of the complaints of Hosea that the people of his day swore falsely when they made a covenant (Hosea 10:4). Judgment would attend such wanton disregard of the solemnity of an oath. Certain civil situations in Israel called for an oath (Exodus 22:10–11; Leviticus 5:1; 6:3; Numbers 5:11–28). This practice set a pattern for the Israelite covenantal oath of allegiance to God.
Christ taught that oaths were binding (Matthew 5:33). In the kingdom of God oaths would become unnecessary (Matthew 5:34–37). At his trial before Caiaphas, Jesus heard an oath from the high priest (Matthew 26:63–65). Paul swore by an oath on occasion (2 Corinthians 1:23; Galatians 1:20). God himself was bound by his own oath (Hebrews 6:13–18) to keep his promise to the patriarchs (Genesis 50:24; Psalms 89:19–37, 49; 110:1–4).