Not all covenants of the Bible were written. The covenant between Jacob and Laban is an example of this. After a hostile confrontation, they made a covenant between themselves by taking oaths before God, making a heap of stones and setting up a pillar as their witnesses, and eating a ceremonial meal together which formally initiated the covenant between them. The gathering of the heap of stones, setting up the pillar, and eating together were all part of the oath ritual establishing the covenant.
The Covenant between Jacob and Laban – Genesis 31:43-54
Then Laban replied to Jacob, “…So now come, let us make a covenant, you and I, and let it be a witness between you and me.” Then Jacob took a stone and set it up as a pillar. Jacob said to his kinsmen, “Gather stones.” So they took stones and made a heap, and they ate there by the heap. Now Laban called it Jegar-sahadutha, but Jacob called it Galeed. Laban said, “This heap is a witness between you and me this day.” Therefore it was named Galeed, and Mizpah, for he said, “May the LORD watch between you and me when we are absent one from the other. If you mistreat my daughters, or if you take wives besides my daughters, although no man is with us, see, God is witness between you and me.” Laban said to Jacob, Behold this heap and behold the pillar which I have set between you and me. This heap is a witness, and the pillar is a witness, that I will not pass by this heap to you for harm, and you will not pass by this heap and this pillar to me, for harm. The God of Abraham and the God of Nahor, the God of their father, judge between us.” So Jacob swore by the fear of his father Isaac. Then Jacob offered a sacrifice on the mountain, and called his kinsmen to the meal; and they ate the meal and spent the night on the mountain.
In the covenant between Jacob and Laban there was no covenant document. However, the covenant rituals were what created the covenant. The rituals had real significance. They were not random historical events. In the covenants of the Bible, not all of the details of the initiatory ceremony are often not given. However, when they are not mentioned they are assumed.1
1 George Wesley Buchanan, “The Covenant in Legal Context,” in The Concept of the Covenant in the Second Temple Period, ed. Stanley E. Porter and Jacqueline C. R. de Roo, Supplements to the Study of Judaism 71. ed. John J. Collins (Atlanta: SBL, 2007), 31-32.