John Gill Commentary 2 Samuel 7:29

"now therefore let it please thee to bless the house of thy servant, that it may continue for ever before thee; for thou, O Lord Jehovah, hast spoken it: and with thy blessing let the house of thy servant be blessed for ever." — 2 Samuel 7:29 (ASV)

Now therefore let it please you to bless the house of your
servant
Not according to the merits of him or his family, but according to the sovereign will and pleasure of God.

The Targum is, begin and bless; let the promised blessings begin to descend, that there may be some appearance of the performance of the promise, which may give encouragement that the whole will be fulfilled:

that it may continue for ever before you ;
under his care and protection:

for you, O Lord God, has spoken [it] ;
whose words never fall to the ground, but have a sure accomplishment:

and with your blessing let the house of your servant be blessed for ever ;
even both with temporal and spiritual blessedness.