O St. Peter, chief of the apostles, incline to us, I beg, thy holy ears, and hear me thy servant whom thou has nourished from infancy, and whom, until this day, thou hast freed from the hand of the wicked, who have hated and do hate me for my faithfulness to thee. Thou, and my mistress the mother of God, and thy brother St. Paul are witnesses for me among all the saints that thy holy Roman church drew me to its helm against my will; that I had no thought of ascending thy chair through force, and that I would rather have ended my life as a pilgrim than, by secular means, to have seized thy throne . for the sake of earthly glory. And therefore I believe it to be through thy grace and not through my own deeds that it has pleased and does please thee that the Christian people, who have been especially committed to thee, should obey me. And especially to me, as thy representative and by thy favour, has the power been granted by God of binding and loosing in Heaven and on earth. On the strength of this belief therefore, for the honour and security of thy church, in the name of Almighty God, Father, Son and Holy Ghost, I withdraw, through thy power and authority, from Henry the king, son of Henry the emperor, who has risen against thy church with unheard of insolence, the rule over the whole kingdom of the Germans and over Italy. And I absolve all Christians from the bonds of the oath which they have made or shall make to him; and I forbid any one to serve him as king. For it is fitting that he who strives to lessen the honour of thy church should himself lose the honour which belongs to him. And since he has scorned to obey as a Christian, and has not returned to God whom he had deserted-holding intercourse with the excommunicated; practising manifold iniquities; spurning my commands which, as thou dost bear witness, I issued to him for his own salvation; separating himself from thy church and striving to rend it-I bind him in thy stead with the chain of the anathema. And, leaning on thee, I so bind him that the people may know and have proof that thou art Peter, and above thy rock the Son of the living God hath built His church, and the gates of Hell shall not prevail against it.

from Gregory VII, Reg. III, No. 10 a, translated in Ernest F. Henderson, Select Historical Documents of the Middle Ages, (London: George Bell and Sons, 1910), 376-377

(http://www.fordham.edu/halsall/source/g7-ban1.html)