Promises are only as good as the one who makes them. A swear is usually uttered in desperation by someone trying to convince.
If one is forced to declare “I promise…” or “I swear to…” it usually means they are not believable and must up the ante to make themselves credible.
Most of the divine promises proclaimed in scripture are not prefaced with “I promise…” or “I swear to you that…” They were just statements made by one that can be trusted.
In the historical account of our rebellion against God recorded in Genesis 3, God pronounced the consequences to the serpent for his role in the rebellion. He didn’t say I promise, or I swear to you that. He simply said because of that, this is the consequence.
The dependability and trustworthiness of God’s word and character are what transform a statement into a promise.
Jesus echoed this truth when he said to let your yes be yes and your no be no (Matthew 5:36-37).
God simply told the serpent that one day a child born of a woman will destroy you and bring an end to your lies, deceit and conquer death. Because of who spoke those words, that statement is a promise. Jesus was that child born of a woman.
A bumper sticker reads “God said it, I believe it, that settles it.” The middle line is not needed: “If God said it, that settles it.”