1. Kings 1:32-35 1. Kgs. 1:32-35
32 And king David said, Call me Zadok the priest, and Nathan the prophet, and Benaiah the son of Jehoiada. And they came before the king. 33 The king also said unto them, Take with you the servants of your lord, and cause Solomon my son to ride upon mine own mule, and bring him down to Gihon: 34 And let Zadok the priest and Nathan the prophet anoint him there king over Israel: and blow ye with the trumpet, and say, God save king Solomon. 35 Then ye shall come up after him, that he may come and sit upon my throne; for he shall be king in my stead: and I have appointed him to be ruler over Israel and over Judah.
1. Chronicles 23:1 1. Chr. 23:1
So when David was old and full of days, he made Solomon his son king over Israel.