'Mouth of the Lord' in the Bible

But if you refuse and rebel,you will be devoured by the sword.”For the mouth of the Lord has spoken.

And the glory of the Lord will appear,and all humanity together will see it,for the mouth of the Lord has spoken.

then you will delight yourself in the Lord,and I will make you ride over the heights of the land,and let you enjoy the heritage of your father Jacob.”For the mouth of the Lord has spoken.