Gregory the Dialogist

1. Above, when the matter of ordaining a king was being discussed, it was said of him who by divine judgment was to be preferred over the rest, that he was chosen and good. Likewise, concerning him already chosen for the kingdom and set in the midst of the people, Samuel said: "Surely you see whom the Lord has chosen, for there is none like him among all the people" (1 Sam. 9:24). …

Commentary on 1 Kings, Book 5, Chapter 3 ↗

Bede

Saul was one year old when he began to reign, etc. The sense is this: after Saul was elected, and anointed by the blessed Samuel with holy oil as king, he remained humble and similar to a private person for the whole first year, nor did he care to dress in royal attire and take up the other insignia of the kingdom: which was also proven above at the time of the Ammonite war where he was driving oxen from the field as a rustic, the beginning of which war Josephus reports happened after a month of all his honor. …

Commentary on Samuel ↗