1 Samuel 9:23

And Samuel said unto the cook, Bring the portion which I gave thee, of which I said unto thee, Set it by thee.

Samuel had reserved the choicest portion of the feast beforehand for Saul. That portion was the shoulder, the most honorable joint. By calling for it to be brought and set before Saul, Samuel honored him and marked him for special honor. This was done openly before the principal men of the town and the assembled guests.

After the feast Samuel took Saul to his own home. There he spoke with him about the principles on which the government of Israel had been established. This conversation was meant to prepare Saul for his future office.