And Nathan said to the king, Go, do all that is in thine heart; for the LORD is with thee. Nathan said to the king - In this case he gave his judgment as a pious and prudent man, not as a prophet; for the prophets were not always under a Divine afflatus; it was only at select times they were thus honored.
For the Lord is with thee - Thou hast his blessing in all that thou doest, and this pious design of thine will most certainly meet with his approbation.