In Genesis 12:7, God tells Abram that He is going to give him the land. Then the Lord appeared to Abram and said, "To your descendants I [God] will give this land."
Abraham reiterates this promise from God in Genesis 24:7, when seeking a wife for his son Isaac Then, in Genesis 26:1, the Lord appears to Isaac and directly tells him the same covenant.
Dwell in this land, and I [God] will be with you and bless; for to you and your descendants I give all these lands, and I will perform the oath which I swore to Abraham your father. (Genesis 26:1 NKJV)
In Genesis 48:4, Jacob tells Joseph, God said to him, "Behold...I will make of you a multitude of people, and give this land to your descendants after you as an everlasting possession."
God's land promise to Abraham's physical descendants was passed down from generation to generation as noted in Exodus 32:13; Deuteronomy 31:21; as well as Deuteronomy 34:4, which states:
Then the Lord said to him [Moses], This is the land of which I swore to give Abraham, Isaac, and Jacob, saying, 'I will give it to your descendants.'
God's covenant is an unconditional promise meaning it is not based on the Israelites meeting any criteria. When God promises Abram, "I will..." He literally means he is going to give them the land, forever.