It is in the power of my hand to do you hurt - Literally, My hand is unto God to do you evil, i.e., I have vowed to God that I will punish thee for thy flight, and the stealing of my teraphim; but the God of Your father has prevented me from doing it. It is a singular instance that the plural pronoun, when addressing an individual, should be twice used in this place - the God of your father, אביכם abichem, for אביך abicha, thy father.

Because.

Genesis 31:26,27 And Laban said to Jacob, What have you done, that you have stolen away unawares to me, and carried away my daughters...

Genesis 20:11 And Abraham said, Because I thought, Surely the fear of God is not in this place; and they will slay me for my wife's sake.

Proverbs 29:25 The fear of man brings a snare: but whoever puts his trust in the LORD shall be safe.

Epistle Xlix. To Anastasius, Bishop of Antioch .
To Anastasius, Bishop of Antioch [35] . Gregory to Anastasius, &c. I received the letters of thy Fraternity, rightly holding fast the profession of the faith; and I returned great thanks to Almighty God, who, when the shepherds of His flock are changed, still, even after such change, guards the faith which He once delivered to the holy Fathers. Now the excellent preacher says, Other foundation can no man lay than that is laid, which is Christ Jesus (1 Cor. iii. 2). Whosoever, then, with love of …
Saint Gregory the Great—the Epistles of Saint Gregory the Great