Consider the account of the messenger of Macbeth’s exploits.

I'm thinking that you are referring to the account of of the Captain in the army telling King Duncan and company what a fantastic and loyal soldier Macbeth was in the battle.

But all’s too weak, For brave Macbeth—well he deserves that name— Disdaining fortune, with his brandished steel, Which smoked with bloody execution, Like valor’s minion carved out his passage Till he faced the slave; Which ne'er shook hands, nor bade farewell to him, Till he unseamed him from the nave to th' chops, And fixed his head upon our battlements.

This sets us up for meeting Macbeth and our expectations that Macbeth might easily resist or dismiss the witch's prophesies.