In Hebrews 6:13 and 16 Paul expresses the significance of the divine oath. In a court of law men assure one another that what they are about to testify is the truth by solemnly swearing to that effect. One’s oath is supposed to be considered true or as close to the truth as the oath taker is able to express and make known. The oath taker swears by someone greater than he (verse-16), which is sometimes by God (Genesis 4:26; 24:3; Deuteronomy 6:13) but at times, as is today’s custom, by the state. Therefore, anyone who lies under oath in a state court is liable to be punished by the state. Under the Old Covenant those who lied with an oath to God were punished by him (Exodus 20:7; Ecclesiastes 5:4-6).
When God made a promise to Abraham, he confirmed that promise with an oath. However, since men swear by one greater than themselves, and since there is none greater than God, the Lord chose to swear by himself (Hebrews 6:13), by his own integrity, that he would do what he promised Abraham. God promised Abraham that he would make him a great nation (Genesis 12:1-4; cp. Hebrews 6:14), which would begin with the birth of his son by Sarah (Genesis 17:15-17), and his descendants would be as the stars of heaven in number, and all the nations of the world would be blessed in him (Genesis 22:15-20).
When Abraham left Haran (Genesis 12:4), he was seventy-five years old, and Isaac was born when Abraham was one-hundred years old (Genesis 21:1-5), which would mean he waited twenty-five years for God to keep his promise. However, Stephen tells us that God first spoke to Abraham, while he was yet in Mesopotamia (Acts 7:2; cf. Genesis 11:31), and he waited in Haran until the death of his father (Acts 7:4). Therefore, Abraham could have waited in Haran years before he left, if it was as much as 15 years, Abraham would have waited 40 years before God fulfilled his promise. If forty years is logical and true, then the believers in Judea would have waited as long as Abraham did for the Lord to fulfill his promise (Hebrews 6:15).
When men find it difficult to keep their word, they often try to compromise in order to be able to say they kept their promises. Lawyers make a living off the technicalities of the law and the technicalities of what was said under contract. So, if the law has been broken, a lawyer might be able to find a technicality, which, if understood in the light of the lawyer’s explanation, would show that the law hadn’t been broken after all. Under the same principle (or lack thereof) a lawyer might be able to offer his client an easier path to fulfilling a contract with another party without actually doing what the contract made him liable to perform. Under these terms the lawyer’s client is able to cheat the party with whom he is under contract out of what was expected, and force him to accept a less desirable arrangement.
With this in mind, Abraham was willing to show God that he was ready to accept the less desirable arrangement by having a son through Sarah’s handmaid. While Ishmael was certainly Abraham’s son, he was Sarah’s son only by a technicality in the law at that time that governed slave ownership (Genesis 16:1-4). Nevertheless, God told Abraham that he neither needed nor desired his help in fulfilling his promise to him. God’s promise was true, not technically so, but God was true to his word as its intended meaning had been received by Abraham in the beginning. In other words the Lord gave his oath for Abraham’s benefit and for the benefit of Abraham’s descendants. Oath making was a human custom that expressed both solemnity and truth. God condescended to this custom and gave his solemn oath to Abraham (Hebrews 6:17), and he would not sacrifice one jot or one tittle in order to fulfill his word (cp. Matthew 5:18).
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