King David's heartfelt thanksgiving to God marks the final, decisive moment in the transfer of royal power to his son, Solomon. The transition is absolute and takes effect immediately. God has granted David a son to occupy the royal seat on this very day [מצודת דוד]. The specific timing of this event is highly significant. By establishing the rule on this exact day, Solomon assumes full royal authority right then and there, even while David is still alive and reigning. Because the kingship is active immediately, anyone who challenges Solomon's authority is instantly classified as a rebel against the crown, an offense punishable by death [מלבי״ם].
Furthermore, by taking his place directly on David's royal seat, Solomon inherits the kingdom in its entirety. This absolute succession completely removes any possibility that the realm might be split or shared among David's other sons [מלבי״ם]. David offers profound gratitude for the privilege of witnessing this transition firsthand, thankful that God allowed him to see his successor securely established during his own lifetime [ביאור שטיינזלץ].