5:2 The words led Israel out speak of David’s service as a military leader during Saul’s reign. The word shepherd is a vivid metaphor of the relationship between a king and his people. The Scriptures apply this metaphor both to God and to human rulers (Ps. 23:1; Ezek. 34:1–10).
5:2 David unites Israel and Judah under one head, fulfilling God’s prophetic purpose (1 Sam. 16:1) and prefiguring the greater unity of God’s people to be accomplished in Christ (1 Corinthians 12; Eph. 4:1–16).
5:2 were leading Israel in and out Referring to David’s leadership in battle (compare 1 Sam 18:5, 13, 16; 19:8).
shall be the shepherd of See 1 Sam 9:3 and note.
the leader The Hebrew word used here is nagid, which can also be translated “ruler.”
5:2 led out and brought in Israel. An idiom for leading military campaigns (1 Sam. 18:13, 16). The second reason for wanting to make David king was his military success (1 Sam. 17:32, 45–47; 18:7; 25:28).
the Lord said to you. The third reason is David’s divine appointment (1 Sam. 16:1 note).
shepherd. This designation is often used metaphorically in the Bible, either for God (Gen. 49:24; Ps. 23:1; 80:1; etc.), for His Son Jesus (John 10:11; Heb. 13:20; 1 Pet. 5:4; Rev. 7:17; etc.), or for divinely appointed human leaders (7:7; Num. 27:15–17; etc.). The image is one of intimate, caring leadership (v. 12 note).
5:2 Robert Bergen notes, “Though the prophetic revelation regarding David in v. 2 was not presented in the preceding narratives, it is consistent with other biblical claims relating to him” (cp. 1Sm 13:14; 25:30; Ps 78:71).
 Sproul, R. C. (Ed.). (2005). The Reformation Study Bible: English Standard Version (p. 433). Orlando, FL; Lake Mary, FL: Ligonier Ministries.