Probably St. Thomas Aquinas

O God, who in this wondrous sacrament hast left unto us a memorial of thy passion; grant us so to venerate the sacred mysteries of thy body and blood, that we may ever continue to feel within ourselves the blessed fruit of thy redemption. Who.

Deus qui nobis sub sacramento mirabili passionis tuae memoriam reliquisti, tribue, quaesumus, ita nos corporis et sanguinis tui sacra mysteria venerari, ut redemptionis tuae fructum in nobis iugiter sentiamus.

Or

ut tuae redemptionis fructum

or

ut tui redemptionis fructum

or

ut redemptionis tui fructum.

     Probably St. Thomas Aquinas (Corpus Thomisticum:  "authenticitate probabile").  Officium de festo Corporis Christi, ad mandatum Urbani Papae IV (Orvieto, July-August 1264).  Latin from Corpus Thomisticum, passim.  "Certainly the text as it now stands in the current Roman rite or Dominican rite did not come from Thomas.  The text in the current liturgical books of the Church is that of the fifteenth-century Roman liturgy, which was introduced in the collections of Thomas's writings by Antonio Pizzamano only in 1497.  The revised text of the fifteenth century was reformed by Pope Pius V in the sixteenth century, and again by Pius X in the twentieth" (James A. Weisheipl, O.P., Friar Thomas d'Aquino:  his life, thought, and work (New York:  Doubleday, 1974), 177-178 (176-185); prayer itself at 181-182).  "The original text of the Mass ('Cibavit eos') and the office ('Sacerdos in aeternum') have not yet [(i.e. by 1974)] been reconstructed" (400).  Starter bibliography at Corpus Thomisticum.
     Variant translations:

O God, who in this wonderful sacrament, hast left us a perpetual memorial of thy passion:  grant us, we beseech thee, so to reverence the sacred mysteries of thy body and blood, as in our souls to be always sensible of the redemption thou has purchased for us.