Gad first appears in the Bible to persuade David to leave his place of safety in Moab and return to Tribe of Judah, where the insanely jealous King Saul awaited his arrival. Later on, after David was king of Israel and had taken census for Israel, Gad came unto him and rebuked him for his transgression and gave David the freedom to choose what punishment from the LORD that would come upon him. David chose to have a three-day plague. During the plague, which took 70,000 lives, Gad told David to build an altar to God on the threshing floor of Araunah the Jebusite. The burnt offerings from this altar caused the God of Israel to put a stop to the plague.
The threshing floor would later become the site of King Solomon's Temple. Gad served as King David's seer.  Gad authored his own work, like Samuel and Nathan, that chronicles the acts of David.