Jerome

Saul, as it is written in the first book of Kings [Samuel], pronounced a curse on him who ate bread before the evening, and until he had avenged himself upon his enemies. So none of his troops tasted any food while all the people of the land ate. And so binding was a solemn fast once it was proclaimed to the Lord, that Jonathan, to whom the victory was due, was taken by lot and could not escape the charge of sinning in ignorance, and his father's hand was raised against him, and the prayers of the people barely saved him.

Against Jovinianus 2.15 ↗

Gregory the Dialogist

Whence it is also added: (Verse 24.) "And every man of Israel was joined together on that day." Indeed every man is joined to the preacher when no condition of men is left from which those who are converted are not led to a good way of life. But those who are joined to Saul are called men, because whatever we may be in the world, we are admonished to be strong in the service of almighty God. …

Commentary on 1 Kings, Book 5, Chapter 4 ↗

Bede

And the man of Israel was joined to himself on that day. With the enemies scattered in different directions, the Church, divided throughout the whole world, rejoices always with one and the same love of brotherhood.

Commentary on Samuel ↗