John Gill Commentary 1 Chronicles 22:12

"Only Jehovah give thee discretion and understanding, and give thee charge concerning Israel; that so thou mayest keep the law of Jehovah thy God." — 1 Chronicles 22:12 (ASV)

Only the Lord give you wisdom and understanding
To manage and conduct an affair of such importance, as well as to govern the people, as follows:

and give you charge concerning Israel; or, when he gives ,
commits the charge of them to you, sets you king over them:

that you may keep the law of the Lord your God ;
have wisdom and understanding to do that, and make that the rule of all your actions, private and public, in your own house, in the house of God, and in all things relative to that, and in the government of the nation.