2 Nephi 1:16 - 1:20
2 Nephi 1:16 And I desire that ye should remember to observe the statutes and the judgments of the Lord; behold, this hath been the anxiety of my soul from the beginning.
Lehi tells his sons that the motivation behind all his actions has been for their welfare. He has been worried about them since they were born. Their welfare has been his only concern since he became their father.
2 Nephi 1:17 My heart hath been weighed down with sorrow from time to time, for I have feared, lest for the hardness of your hearts the Lord your God should come out in the fulness of his wrath upon you, that ye be cut off and destroyed forever;
Lehi worries about his older sons. Like any parent, he fears for their salvation. With their unsteadiness in living the gospel, he knows the danger they face after he is gone. Right now he fears that the Lord will stopped trying to influence them and without that, they will no longer be looked after by Him.
2 Nephi 1:18 Or, that a cursing should come upon you for the space of many generations; and ye are visited by sword, and by famine, and are hated, and are led according to the will and captivity of the devil.
Lehi knows that the end result of their rebelliousness will be death to their descendents by famine and war among themselves. He knows that they will be under the influence of satan only and that can only lead to a miserable life of captivity and suffering for they and their families.
2 Nephi 1:19 O my sons, that these things might not come upon you, but that ye might be a choice and a favored people of the Lord. But behold, his will be done; for his ways are righteousness forever.
Lehi obviously does not want these things happen to his grandchildren and great grandchildren and his descendents. He wants them to be a blessed people and enjoy the guidance of the Lord so as to help them to have a life of joy and spiritual development.
2 Nephi 1:20 And he hath said that: Inasmuch as ye shall keep my commandments ye shall prosper in the land; but inasmuch as ye will not keep my commandments ye shall be cut off from my presence.
Lehi reminds them all again of the promise he has received from the Lord. If they will keep the commandments they will prosper in the land of promise. If they will not keep the commandments, they will lose the influence of the Lord and they will be destroyed as a NATURAL result.