1 Kings 1:30

Even as I sware unto thee by the Lord God of Israel
And so owns and confirms the truth of what Nathan had suggested to Bathsheba, and she had asserted, ( 1 Kings 1:13 1 Kings 1:17 ) ;

saying, assuredly Solomon thy son shall reign after me, and he shall
sit upon my throne in my stead;
this was the substance of the oath:

even so will I certainly do this day;
perform this oath, and set Solomon on the throne.