Alma 50:16 - 50:20
Alma 50: 16 And thus ended the twentieth year.
The twentieth year of the reign of the judges was thus taken up by the creation of the various defensive moves put in place by Moroni.
Alma 50: 17 And in these prosperous circumstances were the people of Nephi in the commencement of the twenty and first year of the reign of the judges over the people of Nephi.
This continual reinforcement of the Nephite lands went on into the 21st year of the reign of the judges.
Alma 50: 18 And they did prosper exceedingly, and they became exceedingly rich; yea, and they did multiply and wax strong in the land.
What was noticeable was that the people’s individual material circumstances were greatly enhanced. They were becoming richer as to material possessions and many more people were flocking to their standard of freedom and wanting to help with the defense of their country.
Alma 50: 19 And thus we see how merciful and just are all the dealings of the Lord, to the fulfilling of all his words unto the children of men; yea, we can behold that his words are verified, even at this time, which he spake unto Lehi, saying:
This enhancement of material blessing was the fulfillment of the promise made by the Lord to Lehi and all those who keep his commandments, namely that they would be blessed with all their needs and then some.
Alma 50: 20 Blessed art thou and thy children; and they shall be blessed, inasmuch as they shall keep my commandments they shall prosper in the land. But remember, inasmuch as they will not keep my commandments they shall be cut off from the presence of the Lord.
To reiterate, the Lord said that if one will keep the commandments they would prosper where ever they were living. If they did not, then they would be cut off from the present of the Lord and would suffer the slings and arrows on misfortune.