Now out of the 3 different Israels that scripture confirms which Israel are the promises to ? This includes the land promise as well.
Lets first look at the promises made to Abraham, who is the representative head of both physical and spiritual seed of Israel the Father of all who believe per Rom 4:16-17
16Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, [Believing Israel]
17(As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were.
Now as we observe these promises to Abraham it is very important to see that there are two types of promises made to Abraham, those that included Him in the promise and those that did not include him.
Now lets look at one of the covenant promises to Him but did not include him !
Gen 12:6-7
6And Abram passed through the land unto the place of Sichem, unto the plain of Moreh. And the Canaanite was then in the land.
7And the LORD appeared unto Abram, and said, Unto thy seed will I give this land: and there builded he an altar unto the LORD, who appeared unto him.
This is a promise to give Abraham's physical seed the land of canaan..But this promise was not given to Abraham personally and it was not stated in this promise how long the physical seed of Abram would have this land..
The promise of Abraham's physical seed receiving land without Him appears again in Gen 15:18-21
18In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates:
19The Kenites, and the Kenizzites, and the Kadmonites,
20And the Hittites, and the Perizzites, and the Rephaims,
21And the Amorites, and the Canaanites, and the Girgashites, and the Jebusites.
And again its mentioned by Abraham Gen 24:7
7The LORD God of heaven, which took me from my father's house, and from the land of my kindred, and which spake unto me, and that sware unto me, saying, Unto thy seed will I give this land; he shall send his angel before thee, and thou shalt take a wife unto my son from thence.
And again, in these references it never speaks of Abraham being made a promise to have this land, but His seed, physical descendants, and not once is it said by God for how long they would have this physical land of canaan...
Now another covenant promise was made to Abraham in scripture which did include Him in the promise Gen 12:1-3
1Now the LORD had said unto Abram, Get thee out of thy country, and from thy kindred, and from thy father's house, unto a land that I will shew thee:
2And I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing:
3And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
Gen 13:15-17
15For all the land which thou seest, to thee will I give it, and to thy seed for ever.
16And I will make thy seed as the dust of the earth: so that if a man can number the dust of the earth, then shall thy seed also be numbered.
17Arise, walk through the land in the length of it and in the breadth of it; for I will give it unto thee.
Notice this promise God specifically says to Abram that He would give it personally to Abraham, and so the words to thee is used..
For this promise is to both Abraham and His seed both and the possession of this land is eternal..
This covenant promise is spoken again in Gen 17:5-8
5Neither shall thy name any more be called Abram, but thy name shall be Abraham; for a father of many nations have I made thee.
6And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee.
7And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee.
8And I will give unto thee, and to thy seed after thee, the land wherein thou art a stranger, all the land of Canaan, for an everlasting possession; and I will be their God.
For this is also confirmed to Isaac and Jacob Gen 26:1-5
1And there was a famine in the land, beside the first famine that was in the days of Abraham. And Isaac went unto Abimelech king of the Philistines unto Gerar.
2And the LORD appeared unto him, and said, Go not down into Egypt; dwell in the land which I shall tell thee of:
3Sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these countries, and I will perform the oath which I sware unto Abraham thy father;
4And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
5Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
Gen 28:12-15
12And he dreamed, and behold a ladder set up on the earth, and the top of it reached to heaven: and behold the angels of God ascending and descending on it.
13And, behold, the LORD stood above it, and said, I am the LORD God of Abraham thy father, and the God of Isaac: the land whereon thou liest, to thee will I give it, and to thy seed;
14And thy seed shall be as the dust of the earth, and thou shalt spread abroad to the west, and to the east, and to the north, and to the south: and in thee and in thy seed shall all the families of the earth be blessed.
15And, behold, I am with thee, and will keep thee in all places whither thou goest, and will bring thee again into this land; for I will not leave thee, until I have done that which I have spoken to thee of.
And so thats why the writer of Hebrews writes that Isaac and Jacob were heirs together of the same promise Heb 11:8-10
8By faith Abraham, when he was called to go out into a place which he should after receive for an inheritance, obeyed; and he went out, not knowing whither he went.
9By faith he sojourned in the land of promise, as in a strange country, dwelling in tabernacles with Isaac and Jacob, the heirs with him of the same promise:
10For he looked for a city which hath foundations, whose builder and maker is God.
And this land, inheritance which they sought as a result of the promise was heavenly:
Heb 11:13-16
13These all died in faith, not having received the promises, but having seen them afar off, and were persuaded of them, and embraced them, and confessed that they were strangers and pilgrims on the earth.
14For they that say such things declare plainly that they seek a country.
15And truly, if they had been mindful of that country from whence they came out, they might have had opportunity to have returned.
16But now they desire a better country, that is, an heavenly: wherefore God is not ashamed to be called their God: for he hath prepared for them a city.
This land or country they sought was not a physical plot of land in the middle east, but a heavenly hope, for as a result of this promise they considered themselves strangers and pilgrims of this earth, because their land promise, their country promise was heavenly..
BTW, it is this heavenly hope of the Fathers that Paul meant here in Acts 26:6-8
6And now I stand and am judged for the hope of the promise made of God, unto our fathers:
7Unto which promise our twelve tribes, instantly serving God day and night, hope to come. For which hope's sake, king Agrippa, I am accused of the Jews.
8Why should it be thought a thing incredible with you, that God should raise the dead?
Amen, the Land, the Country thast the True Fathers hoped for, was only to be attained through the resurrection of the dead, a heavenly hope, the same peter writes about 1 Pet 1:3-4
3Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
4To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you,
This is the same promise that Abraham, Isaac, and Jacob had from those promises made them personally in genesis..