What does 1 Samuel 16:21 mean?
God has rejected Saul as king of Israel and removed His Spirit (1 Samuel 13:11–14; 15:17–29; 16:14), but Saul retains the throne for at least ten more years. At God's direction, Samuel has anointed David as Israel's next king, and God's Spirit has come upon him (1 Samuel 16:1–13). The rest of 1 Samuel follows Saul and David as one fades from the kingship of Israel and the other rises. Here they meet for the first time. Most likely, at this time, neither knows that David has been anointed to be the next king of Israel.David's outstanding qualities have been listed by one of Saul's servants (1 Samuel 16:18). Saul truly admires young David. David served Saul, and Saul is said here to have loved David. Before long, David was promoted from simply playing music for the king to being his armor-bearer. The armor-bearer not only carried his master's weapons into battle, but also fought alongside him. Ideally, an armor-bearer was closer to his master than any other servant. A warrior trusted his armor-bearer with his life (1 Samuel 14:6–14).
The bond between Saul and David grew quickly with neither suspecting what was to come.