Genesis 26:31-33

Young's Literal Translation

³¹ and rise early in the morning, and swear one to another, and Isaac sendeth them away, and they go from him in peace.

³² And it cometh to pass during that day that Isaac's servants come and declare to him concerning the circumstances of the well which they have digged, and say to him, `We have found water;'

³³ and he calleth it Shebah, [oath,] therefore the name of the city [is] Beer-Sheba, [well of the oath,] unto this day.