Reflecting on the friendship between Jonathan and David, it is important to realize that they were not the same age. When Jonathan was first introduced, he was an army commander and so he must have been at least twenty years old (see Numbers 1:3; 1 Samuel 13:2). If Saul began his reign at the age of thirty and ruled for around forty years (Acts 13:21), then Jonathan was close to fifty when he died with his father (1 Samuel 31:1–13). David was about thirty years old when Saul died (see 1 Samuel 31:2; 2 Samuel 5:4), thus he must have been around twenty years younger than Jonathan.1
3 Then Jonathan made a covenant with David, because he loved him as his own soul.