Samuel judged Israel as long as he lived. 1 Sam 7:15-16
In his old age Samuel appointed his sons judges over Israel. …His sons did not follow his example but sought illicit gain and accepted bribes, perverting justice. 1 Sam 8:1-7
Therefore all the elders of Israel … said to [Samuel], “…, appoint a king over us, as other nations have, to judge us.” … the LORD, … said (to Samuel) … “Grant the people’s every request. It is not you they reject, they are rejecting me as their king. 1 Sam 8:1-7
So …
…, Samuel poured oil on Saul’s head … saying: “The LORD anoints you commander over his heritage. You are to govern the LORD’S people Israel, … 1 Sam 10:1
Wherever he turned, [Saul] was successful 1 Sam 14:47
But then Saul decided to do things his way instead of God’s way. So …
1 Sam 15:1-19
… Samuel said: “… Because you have rejected the command of the LORD, he, too, has rejected you as ruler.” 1 Sam 15:22-23
Then Samuel, with the horn of oil in hand, anointed [David] in the midst of [David’s] brothers; and from that day on, the spirit of the LORD rushed upon David 1 Sam 16:13