Dates: c. 400 · Wikipedia
Summary: The Liturgy of Saint James, the historic anaphora of Jerusalem and Antioch, offers the Eucharistic sacrifice "for the rest of the souls that have fallen asleep aforetime" and prays God to "give rest" to all the faithful departed "from righteous Abel unto this day." It is the most fully developed of the early Eastern witnesses to intercession for the dead within the offering of the sacrifice.
… and grant that our offering may be acceptable, sanctified by the Holy Spirit, as a propitiation for our transgressions and the errors of the people; and for the rest of the souls that have fallen asleep aforetime.
— The Divine Liturgy of James, source. The Eucharistic offering is explicitly described as availing not only "for our transgressions and the errors of the people" but "for the rest of the souls that have fallen asleep aforetime" — the sacrifice presented on behalf of the dead, that they may have rest.
Remember, O Lord God, the spirits and all flesh, of whom we have made mention, and of whom we have not made mention, who are of the true faith, from righteous Abel unto this day: unto them do Thou give rest there in the land of the living, in Thy kingdom, in the joy of paradise, in the bosom of Abraham, and of Isaac, and of Jacob, our holy fathers; whence pain, and grief, and lamentation have fled.
— The Divine Liturgy of James, source. The great intercession names "the spirits and all flesh … from righteous Abel unto this day" and asks God to "give rest" to them "in the bosom of Abraham" — the same Abraham's-bosom imagery used elsewhere on this wiki for the intermediate state, here invoked as the object of the Church's prayer for the dead.