Covenant of the pieces

According to the Hebrew Bible, the covenant of the pieces or covenant between the parts (Hebrew: ברית בין הבתרים "berith bein hebětarim") was an event in which God revealed himself to Abraham and made a covenant with him, in which God announced to Abraham that his descendants would eventually inherit the Land of Israel. This was one of the first in a series of covenants made between God and the biblical patriarchs.
Biblical narrative.
The biblical story in recounts the covenant of the pieces. The day started with a vision in which Abram expressed his concerns about being childless. God tells Abram that he would have a son born to him, asks him to count the stars, if possible, and promises "So shall thy seed be." God commands Abram to prepare an animal sacrifice. Abram performed the sacrifice, cutting the animals (except the birds) into two pieces.
As the sun was going down, Abram fell into a deep sleep. God prophesied to Abram that his seed would be strangers in a land that is not theirs (a strange land) and serve the rulers of the land for four hundred years but afterward, they would come out with "great substance" and in the fourth generation, they would return to Canaan.
Yahweh declared all of the regions of land that Abram's offspring would claim: 
The covenant found in is known in Hebrew as the "Brit bein HaBetarim", the "Covenant Between the Parts." The covenant was for Abraham and his seed, or offspring, both of natural birth and adoption.
In Genesis 12–17 three covenants (or developments of the covenant) can be distinguished. According to the documentary hypothesis these covenants are based on the differing Jahwist, Elohist and Priestly sources. In Genesis 12 and 15, God grants Abram land and descendants but does not place any stipulations (unconditional). By contrast, Gen. 17 contains the covenant of circumcision (conditional).