A historical English prayer collected in Prayers of the Middle Ages: Light from a Thousand Years, edited by J. Manning Potts.
Historical edition. Historical claims and instructions are preserved as historical context.
O God, who purifiest the heart of man from sin, and makest it more white than snow, pour down upon us the abundance of Thy mercy; renew, we beseech Thee, Thy Holy Spirit within us, that we may show forth Thy praise, and, strengthened by Thy grace, may obtain rest in the eternal mansions of the heavenly Jerusalem; through our Lord Jesus Christ. Amen.