"grant, we pray, that Christian hope may draw us onward to where our nature is united with you"

"Almighty, ever-living God, who allow those on earth to celebrate divine mysteries, grant, we pray, that Christian hope may draw us onward to where our nature is united with you.  Through."

"Omnipotens sempiterne Deus, qui in terra constitutos divina tractare concedis, praesta, quaesumus, ut illuc tendat christianae devotionis affectus, quo tecum est nostra substantia.  Per."

Almighty, ever-living God, who allow those stationed on earth to handle [things] divine, grant, we pray, that to that place may tend the affection of Christian devotion where with you is our nature [(substantia)].  Through.

     Prayer after Communion "At the Mass during the Day" of the Ascension, Roman Missal.  The core of this "Prayer after Communion" is basically no. 185 (which Vogel, following Mohlberg, appears to date between 400 and 440 (Medieval liturgy:  an introduction to the sources (1986 [1981]), 43-44 and 58n127) in the "Sacramentary of Verona, called Leonine" (Verona, Biblioteca Capitolare, cod. 85 (once 80)).  Text of no. 185 from the 1956 edition ed. Mohlberg, where it is assigned to "nach 440" and later (groups 13, 27, etc. ("Die Datierungsversuche," pp. lxix ff.) is as follows:

Tribue, quaesumus domine, ut illuc tendat christianae nostrae deuotionis a(f)fectus, quo tecum est nostra substantia:  per.

More (less well-organized) here.