7 He also said to him, “I am the LORD, who brought you out of Ur of the Chaldeans to give you this land to take possession of it.”
8 But Abram said, “O Sovereign LORD, how can I know that I will gain possession of it?”
9 So the LORD said to him, “Bring me a heifer, a goat and a ram, each three years old, along with a dove and a young pigeon.”
10 Abram brought all these to him, cut them in two and arranged the halves opposite each other; the birds, however, he did not cut in half. 11 Then birds of prey came down on the carcasses, but Abram drove them away.
12 As the sun was setting, Abram fell into a deep sleep, and a thick and dreadful darkness came over him. 13 Then the LORD said to him, “Know for certain that your descendants will be strangers in a country not their own, and they will be enslaved and mistreated four hundred years. 14 But I will punish the nation they serve as slaves, and afterward they will come out with great possessions. 15 You, however, will go to your fathers in peace and be buried at a good old age. 16 In the fourth generation your descendants will come back here, for the sin of the Amorites has not yet reached its full measure.”
17 When the sun had set and darkness had fallen, a smoking firepot with a blazing torch appeared and passed between the pieces. 18 On that day the LORD made a covenant with Abram and said, “To your descendants I give this land, from the river of Egypt to the great river, the Euphrates— 19 the land of the Kenites, Kenizzites, Kadmonites, 20 Hittites, Perizzites, Rephaites, 21 Amorites, Canaanites, Girgashites and Jebusites.” (Genesis 15:7-21)

21 “If, however, he is poor and cannot afford these, he must take one male lamb as a guilt offering to be waved to make atonement for him, together with a tenth of an ephah of fine flour mixed with oil for a grain offering, a log of oil, 22 and two doves or two young pigeons, which he can afford, one for a sin offering and the other for a burnt offering. (Leviticus 14:21-3)