Let’s look at those two verses together to answer your good question.  2 Chronicles 15:2 says, “And he went out to meet Asa, and said unto him, Hear ye me, Asa, and all Judah and Benjamin; The LORD is with you, while ye be with him; and if ye seek him, he will be found of you; but IF YE FORSAKE HIM, HE WILL FORSAKE YOU.”  Hebrews 13:5 says, “Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I WILL NEVER LEAVE THEE, NOR FORSAKE THEE.”  Since Hebrews 13:5 is a quote from the Old Testament, let’s look at that, also.  Deuteronomy 31:6 says, “Be strong and of a good courage, fear not, nor be afraid of them: for the LORD thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee.”  (Also read Joshua 1:5 and 1 Chronicles 28:20.) 

It is interesting that we see Azariah warning King Asa, along with the tribes of Judah and Benjamin that the Lord’s loyalty to them depended on their loyalty to Him.  It is good to consider the events in chapter 14, where we see the Lord blessing His people greatly under the leadership of King Asa.  Asa “did that which was good and right in the eyes of the LORD his God.” (verse 2).  He “commanded Judah to seek the LORD God of their fathers, and to do the law and the commandment.” (verse 4).  Then, in verse 7, we read, “Therefore he said unto Judah, Let us build these cities, and make about them walls, and towers, gates, and bars, while the land is yet before us; because we have sought the LORD our God, we have sought him, and HE HATH GIVEN US REST ON EVERY SIDE. So they built and prospered.”

In verses 9-12, we see Asa’s army faced with an Ethiopian army of a thousand thousand, and three hundred chariots.  In verse 11, we see such a wonderful and faithful prayer of Asa and the Lord gave them a mighty victory against this massive army.  Asa had begun well. He was faithful to the Lord, but would he continue and end as well as he had begun? When King Asa returned in victory, the prophet, Azariah, met him and delivered his message. It was a needed and timely message, for the danger for God’s people is always the greatest after a victory is won. “The LORD is with you, while ye be with Him; and if ye seek Him, He will be found of you; but if ye forsake Him, He will forsake you.” This has, of course, nothing to do with the question of salvation and the possession of eternal life, which the believer has in Christ. To continue with a real testimony, to have fruit for God, and have the victory at all times, a close walk with the Lord is vital. Without this, God’s people are helpless and will dishonor their Lord. Verses 3-6 show the results of departure from the Lord, such as were among Israel during the period of the judges. So, the people are encouraged to be faithful in verse 7, “Be ye strong therefore, and let not your hands be weak; for your work shall be rewarded.”

I think we can see how this differs from what we read in Hebrews 13:5.  Here, the believer is strengthened against the temptation for greed and discontentment.  “Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee.”  Our “conversation” is speaking of our manner of life.  We can live without being covetous of what others may possess.  We truly can be content when we realize the promise of our God to always be with us…never leaving or forsaking us in our needs.  My fellow believer, let us rejoice in the precious knowledge that the Lord will neither withdraw His presence nor His help.  May we come to understand and rely upon our Lord for all our needs.  “God is our refuge and strength, a very present help in trouble.” (Psalm 46:1).  (CC)  (690.2)