I Samuel - Chapter 10
The Adventures of Saul in the Coat Room
Shmuel anointed Shaul with oil - the commentators differ as to whether this was the shemen hamishcha, the special oil prepared by Moses, which was used to anoint the kings of the Davidic dynasty. Then, Shmuel gave Shaul three signs. First, he would meet two men who would tell him that his lost donkeys were found, and that his father was now looking for him. Next, Shaul would meet three men, bringing kids, loaves of bread and a jug of wine for sacrifices. He was to take the bread that would be offered him. Finally, he would meet a band of prophets and would, himself, be overcome by a spirit of prophecy and become "a different person." After all these signs came to pass, Shaul was to go to Gilgal, where he would be joined by Shmuel, who would offer sacrifices.
All of these things came to pass. When Shaul was prophesying with the prophets, he was seen. The sight amazed the people who coined an expression, "Saul is one of the prophets now?"
Shaul returned home and was met by his uncle. He told his uncle that Shmuel told him the donkeys had been found, but he didn't say anything about being made king.
Shmuel called a gathering at Mitzpah, where he announced that he was going to publicly anoint the king they had demanded. He drew lots Tribe by Tribe, family by family, until he came to Shaul, son of Kish. But when they called his name, the modest Shaul was hiding among the luggage. The people were impressed by the tall, handsome Shaul and proclaimed him their king. Shmuel repeated all the laws of the King, then sent them home. Some lowly people denigrated Shaul, saying he was unfit. He heard, but he let his natural humility win out. He is actually criticized for this, as a king may not forego the honor due him (see Talmud Yoma 22b, end).