5 For that it is His doing that we conquer, and that we attain by the subduing of the adversary to the palm of the greatest contest, the Lord declares and teaches in His Gospel, saying, “But when they deliver you up, take no thought how or what you shall speak; for it shall be given you in that same hour what you shall speak. For it is not you that speak, but the Spirit of your Father which speaks in you.” And again: “Settle it therefore in your hearts, not to meditate before what you shall answer; for I will give you a month and wisdom, which your adversaries shall not be able to resist.” In which, indeed, is both the great confidence of believers, and the gravest fault of the faithless, that they do not trust Him who promises to give His help to those who confess Him, and do not on the other hand fear Him who threatens eternal punishment to those who deny Him.
Source: The Epistles of Cyprian (New Advent)