Albert Barnes Commentary 1 Chronicles 28:7

"And I will establish his kingdom for ever, if he be constant to do my commandments and mine ordinances, as at this day." — 1 Chronicles 28:7 (ASV)

If he is constant - The conditional character of the promise made to David regarding the continuance of his posterity on the Jewish throne (see the marginal reference to 2 Samuel 7:14), is now clearly declared.