Almighty God, who hast given us grace with one accord to make our common supplication unto thee, and dost promise that were two or three are gathered together in thy Name thou wilt grant their requests, fulfill now, O Lord, the desires and petitions of thy servants as may be most expedient for them, granting them in this world knowledge of thy truth, and in the world to come, live everlasting, Amen.
Source: Hymnal of the Evangelical and Reformed Church (antecedent to the United Church of Christ) 1941
The prayer you quote looks familiar. It may be from the third antiphone of the Divine Liturgy of +Basil the Great, the predecessor to the Divine Liturgy of +John Chrysostomos:
“O Thou who hast bestowed on us these common and accordant prayers, and dost promise that when two or three are gathered together in Thy name, Thou wilt grant their requests, fulfill even now the requests of thy servants as is expedient for them, granting us in this present age the knowledge of Thy truth, and in that to come, life eternal.”
Its sad the Fathers are so unknown among Protestants and that many in the Roman Church, and in Orthodoxy for that matter, don’t appreciate the great treasure we have in the writings and lives of The Fathers.