1 Chronicles 21:9

And the LORD spake unto Gad, David's seer, saying,

The Lord spake unto Gad, David's seer. Although David was himself endowed with a prophetic gift, yet, in matters relating to himself or his kingdom, he was in the habit of consulting the Lord through the medium of the priests, and when he failed to do so, a prophet was sent on extraordinary occasions to admonish or chastise him. Gad, a private friend, was occasionally employed as the bearer of these prophetic messages.