1Ki 8:24 “You have kept what You promised Your servant David my father; You have both spoken with Your mouth and fulfilled it with Your hand, as it is this day.
The promises referred to here were made to David in 1Chr 17 :10-14. God promised that He would establish his kingdom and that He would raise up his offspring to succeed him. He also promised that his offspring would build a house for him.
It is during this prayer for the temple dedication where Solomon acknowledges that indeed God had kept His promises. Solomon had already succeeded David and the temple had been constructed.
Num 23:19 “God is not a man, that He should lie, nor a son of man, that He should repent. Has He said, and will He not do it? Or has He spoken, and will He not make it good? Yes He will bring to pass all those promises . He does not only make promises but also keeps them
Further readings:
2 Sam 7:13
1Ki 2:4
1 Chr 17:23
πBlessed Dayπ