Introduction:
Gad, a prophet during the reign of King David, plays a significant role in the biblical narrative as a divine messenger and advisor to the king. His interactions with David are recorded in the books of 1 Samuel, 2 Samuel, and 1 Chronicles. Gad's counsel is pivotal during critical moments in David's life, reflecting the importance of prophetic guidance in the governance and spiritual life of Israel.

Biblical References:

1. Gad's Introduction and Role:
Gad first appears in the biblical narrative as a prophet who joins David during his time of refuge from King Saul. In 1 Samuel 22:5, Gad advises David to leave the stronghold of Moab and return to the land of Judah: "But the prophet Gad said to David, 'Do not stay in the stronghold. Depart, and go into the land of Judah.' So David left and went into the forest of Hereth." This counsel demonstrates Gad's role as a divine guide, ensuring David's safety and alignment with God's will.

2. Gad's Involvement in the Census Incident:
One of the most significant episodes involving Gad is his involvement in the aftermath of David's census of Israel, which displeased the Lord. In 2 Samuel 24:11-13, Gad delivers a message from God offering David three choices of punishment for his sin: "When David got up in the morning, the word of the LORD had come to Gad the prophet, David’s seer: 'Go and tell David that this is what the LORD says: I am offering you three options. Choose one of them, and I will carry it out against you.'" Gad's role here underscores the seriousness of David's actions and the necessity of divine justice.

3. Gad's Instruction for the Altar:
Following the plague that resulted from the census, Gad instructs David to build an altar to the Lord on the threshing floor of Araunah the Jebusite. In 2 Samuel 24:18, Gad's directive is clear: "And that day Gad came to David and said, 'Go up and build an altar to the LORD on the threshing floor of Araunah the Jebusite.'" This act of obedience leads to the cessation of the plague, highlighting the importance of repentance and worship in restoring the relationship between God and His people.

4. Gad's Role in David's Administration:
Gad is also mentioned in 1 Chronicles 21:9-19, where he again advises David regarding the census and the subsequent building of the altar. Additionally, 1 Chronicles 29:29 references Gad as one of the chroniclers of David's reign, indicating his ongoing influence and presence in the king's court: "As for the events of King David’s reign, from beginning to end, they are written in the records of Samuel the seer, the records of Nathan the prophet, and the records of Gad the seer."

Theological Significance:
Gad's interactions with David highlight the role of prophets as intermediaries between God and His chosen leaders. Through Gad, God communicates His will, offers guidance, and enforces divine justice. Gad's presence in David's life serves as a reminder of the necessity for leaders to seek and heed godly counsel, ensuring their actions align with divine purposes.

Conclusion:
Gad's contributions to the biblical narrative emphasize the importance of prophetic ministry in the life of Israel and its leaders. His guidance to David during pivotal moments underscores the need for obedience to God's commands and the value of repentance and worship in maintaining a right relationship with the Lord.