What does 1 Samuel 16:1 mean?

This verse begins a new section of 1 Samuel, shifting to a focus on David.

Samuel has continued to grieve over the Lord's rejection of Saul as Israel's king (1 Samuel 15:23, 34–35). Samuel had anointed Saul as king (1 Samuel 10:1–27; 15:1). The prophet had also warned the people about their desire for a king (1 Samuel 8:1–22; 12:1–25). But he "told the people the rights and duties of the kingship" (1 Samuel 10:25); and Samuel promised to continue to pray for the people and instruct them (1 Samuel 12:23).

In an earlier incident, Saul failed to wait for the prophet and acted on his own in making a sacrifice (1 Samuel 13). Samuel told the king, "You have done foolishly. You have not kept the command of the Lord your God, with which he commanded you. For then the Lord would have established your kingdom over Israel forever. But now your kingdom shall not continue. The Lord has sought out a man after his own heart, and the Lord has commanded him to be prince over his people, because you have not kept what the Lord commanded you" (1 Samuel 13:13–14). Samuel knew that Saul's kingdom would not continue, but apparently God's rejection of Saul himself in the incident with the Amalekites brought an even deeper grief.

We can imagine various things Samuel might have been mourning: that the Israelites had rejected God as their king and requested an earthly king in the first place, that Saul had failed to honor the Lord so egregiously, the dismal outlook for Israel's future, the hardship for Saul, and any number of other troubles. But God now tells Samuel it is time to move on. He can no longer grieve over a person God has rejected. The Lord is sending Samuel out to anoint a new king over Israel.

God tells Samuel to fill a horn with oil and start traveling. He is to go to Jesse the Bethlehemite, one of whose sons will be the next king. This is the first use of the name Jesse and the first mention of Bethlehem in 1 Samuel. Jesse was the grandson of Boaz and Ruth (Ruth 4:17). Bethlehem was about ten miles, or sixteen kilometers, from Samuel's home in Ramah.

Samuel had anointed Saul to be king over Israel with a flask (1 Samuel 10:1). Now the Lord directs Samuel to use a ram's horn. Samuel likely followed the recipes for the anointing oil given in Exodus 30:23–25, which includes a mix of spices in olive oil.