1 Nephi 17: rest of 40

Nephi tells his brothers that the Lord loved their fathers, Abraham, Issac, and Jacob so much that He made a covenant with them. The Abrahamic Covenant is what we call it today. The link takes you to a commentary on the covenant in the Bible Dictionary. It gives the specific references to what was covenanted to him and where it can be found in the Bible. It is an amazing covenant. If we are faithful and join the Church, we can make that covenant with God and be part of the house of Israel, either through actual lineage or adoption.

What a great opportunity because God will not break His part of the covenant, ever. He has also provided a way for us to come back into the covenant if we break our part. When we participate in the covenant of celestial marriage, the marriage performed in the temple, we will have the promise of personal salvation and eternal increase. We will be save and not be stopped in our learning and creation. We will also be together as a family forever. This is a special thing.

Finally, according to the Bible Dictionary article, the covenant with Abraham contained promises of land for his posterity. This is why the Lord prepared the way, through Moses, for the Israelites to be brought out of bondage in Egypt. Nephi knew this, and he mentions it at the end of verse 40.