That 'promise ' came with a condition.... obedience
I suggest looking up the whole passage around these verses....
Gen 17:14 And the uncircumcised man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant.
Gen 26:5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
Lev 26:40 If they shall confess their iniquity, and the iniquity of their fathers, with their trespass which they trespassed against me, and that also they have walked contrary unto me;
Lev 26:41 And that I also have walked contrary unto them, and have brought them into the land of their enemies; if then their uncircumcised hearts be humbled, and they then accept of the punishment of their iniquity:
Lev 26:42 Then will I remember my covenant with Jacob, and also my covenant with Isaac, and also my covenant with Abraham will I remember; and I will remember the land.
Deu 7:12 Wherefore it shall come to pass, if ye hearken to these judgments, and keep, and do them, that the LORD thy God shall keep unto thee the covenant and the mercy which he sware unto thy fathers:
We also know God kept that promise....
Jos 21:43 And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein.
Jos 21:44 And the LORD gave them rest round about, according to all that he sware unto their fathers: and there stood not a man of all their enemies before them; the LORD delivered all their enemies into their hand.
Jos 21:45 There failed not ought of any good thing which the LORD had spoken unto the house of Israel; all came to pass.
I suggest looking up the whole passage around these verses....
Gen 17:14 And the uncircumcised man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant.
Gen 26:5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
Lev 26:40 If they shall confess their iniquity, and the iniquity of their fathers, with their trespass which they trespassed against me, and that also they have walked contrary unto me;
Lev 26:41 And that I also have walked contrary unto them, and have brought them into the land of their enemies; if then their uncircumcised hearts be humbled, and they then accept of the punishment of their iniquity:
Lev 26:42 Then will I remember my covenant with Jacob, and also my covenant with Isaac, and also my covenant with Abraham will I remember; and I will remember the land.
Deu 7:12 Wherefore it shall come to pass, if ye hearken to these judgments, and keep, and do them, that the LORD thy God shall keep unto thee the covenant and the mercy which he sware unto thy fathers:
We also know God kept that promise....
Jos 21:43 And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein.
Jos 21:44 And the LORD gave them rest round about, according to all that he sware unto their fathers: and there stood not a man of all their enemies before them; the LORD delivered all their enemies into their hand.
Jos 21:45 There failed not ought of any good thing which the LORD had spoken unto the house of Israel; all came to pass.