John Calvin (1509-64 AD)

“Although this does not exist in the Latin copies, yet as it accords so well with the whole, we cannot think of omitting it. The words are, THINE IS THE KINGDOM, AND THE POWER, AND THE GLORY, FOR EVER. Here is the calm and firm assurance of our faith. For were our prayers to be commended to God by our own worth, who would venture even to whisper before him? Now, however wretched we may be, however unworthy, however devoid of commendation, we shall never want a reason for prayer, nor a ground of confidence, since the kingdom, power, and glory, can never be wrested from our Father.”

Source: Institutes of the Christian Religion, Vol. III, Of Prayer 20:47