14 We add, also, and say, “Your will be done, as in heaven so in earth;”not that God should do what He wills, but that we may be able to do what God wills. For who resists God, that l He may not do what He wills? But since we are hindered by the devil from obeying with our thought and deed God's will in all things, we pray and ask that God's will may be done in us; and that it may be done in us we have need of God's good will, that is, of His help and protection, since no one is strong in his own strength, but he is safe by the grace and mercy of God.
And further, the Lord, setting forth the infirmity of the humanity which He bore, says, Father, if it be possible, let this cup pass from me' and affording an example to His disciples that they should do not their own will, but God's, He went on to say, “Nevertheless not as I will, but as You will.” And in another place He says, “I came down from heaven not to do my own will, but the will of Him that sent me.” Now if the Son was obedient to do His Father's will, how much more should the servant be obedient to do his Master's will!
As in his epistle John also exhorts and instructs us to do the will of God, saying, “Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world is the lust of the flesh, and the lust of the eyes, and the ambition of life, which is not of the Father, but of the lust of the world. And the world shall pass away, and the lust thereof: but he that does the will of God abides for ever, even as God also abides for ever.” We who desire to abide for ever should do the will of God, who is everlasting.
Source: The Treatises of Cyprian (New Advent)