The Prophet tells of to consider Abraham, the rock from which we were hewn (digged). He is "The Father" of the faithful, who with just him and his wife Sarah achieved a vast number of children that are innumerable. It was he alone that God worked with, given the promises, and developed a great number of nations (The Church), those sheep of another fold, that Christ would bring with Him. We are called to such exploits to achieve our walk of faith.