In the light of your truth confirm us

"May the communion in your Sacrament that we have consumed, save us, O Lord, and confirm us in the light of your truth.  Through."

"Sacramentorum tuorum Domine communio sumpta nos saluet, et in tuae veritatis luce confirmet.  Per."

May the communion of your sacraments, having been taken/received/consumed, save us, O Lord, and in the light of your truth confirm [us].  Through.

     Post communion, Nineteenth Sunday in Ordinary time, Roman missal, second translation mine.  =No. 1216 in the edition of the 8th/9th-century Liber sacramentorum Engolismensis:  Manuscrit B.N. Lat. 816:  Le sacramentaire Gélasien d’Angoulême ed. Saint-Roche (CCSL 159C (1987), 180), who, on pp. XI-XII, proposes the period 768-781 for the sacramentary's composition.  =Corpus orationum no. 5166, where the Gregorianum (no. 654 in the edition ed. Deschusses) is also listed (among many others).