This should help you out.
Cyril of Jerusalem:
"Then [during the Eucharistic prayer] we make mention also of those who have already fallen asleep: first, the patriarchs, prophets, apostles, and martyrs, that through their prayers and supplications God would receive our petition . . . " (Catechetical Lectures 23:9 A.D. 350]).
Ephraim the Syrian:
“You victorious martyrs who endured torments gladly for the sake of the God and Savior, you who have boldness of speech toward the Lord himself, you saints, intercede for us who are timid and sinful men, full of sloth, that the grace of Christ may come upon us, and enlighten the hearts of all of us so that we may love him” (Commentary on Mark A.D. 370]).
“Remember me, you heirs of God, you brethren of Christ; supplicate the Savior earnestly for me, that I may be freed through Christ from him that fights against me day by day” (The Fear at the End of Life A.D. 370]).
Cyprian of Carthage:
“Let us remember one another in concord and unanimity. Let us on both sides [of death] always pray for one another. Let us relieve burdens and afflictions by mutual love, that if one of us, by the swiftness of divine condescension, shall go hence first, our love may continue in the presence of the Lord, and our prayers for our brethren and sisters not cease in the presence of the Father’s mercy” (Letters 56[60]:5 A.D. 253]).
Clement of Alexandria:
“In this way is he [the true Christian] always pure for prayer. He also prays in the society of angels, as being already of angelic rank, and he is never out of their holy keeping; and **though he pray alone, he has the choir of the saints standing with him ** [in prayer]” (Miscellanies 7:12 A.D. 208]).
Origen:
“But not the high priest [Christ] alone prays for those who pray sincerely, but also the angels . . . as also the souls of the saints who have already fallen asleep” (Prayer 11 A.D. 233]).
Methodius:
“Hail to you for ever, Virgin Mother of God, our unceasing joy, for to you do I turn again. You are the beginning of our feast; you are its middle and end; the pearl of great price that belongs to the kingdom; the fat of every victim, the living altar of the Bread of Life [Jesus]. Hail, you treasure of the love of God. Hail, you fount of the Son’s love for man. . . . You gleamed, sweet gift-bestowing Mother, with the light of the sun; you gleamed with the insupportable fires of a most fervent charity, bringing forth in the end that which was conceived of you . . . making manifest the mystery hidden and unspeakable, the invisible Son of the Father—the Prince of Peace, who in a marvelous manner showed himself as less than all littleness” (Oration on Simeon and Anna 14 A.D. 305]).
“Therefore, we pray [ask] you, the most excellent among women, who glories in the confidence of your maternal honors, that you would unceasingly keep us in remembrance. O holy Mother of God, remember us, I say, who make our boast in you, and who in august hymns celebrate the memory, which will ever live, and never fade away” (ibid.).
“And you also, O honored and venerable Simeon, you earliest host of our holy religion, and teacher of the resurrection of the faithful, do be our patron and advocate with that Savior God, whom you were deemed worthy to receive into your arms. We, together with you, sing our praises to Christ, who has the power of life and death, saying, ‘You are the true Light, proceeding from the true Light; the true God, begotten of the true God’” (ibid.).
The Liturgy of St. Basil:
“By the command of your only-begotten Son we communicate with the memory of your saints . . . by whose prayers and supplications have mercy upon us all, and deliver us for the sake of your holy name” (Liturgy of St. Basil A.D. 373]).
Gregory of Nazianz:
“May you [Cyprian] look down from above propitiously upon us, and guide our word and life; and shepherd this sacred flock . . . gladden the Holy Trinity, before which you stand” (Orations 17[24] A.D. 380]).
"**Yes, I am well assured that [my father’s] intercession is of more avail now than was his instruction in former days, since he is closer to God, now that he has shaken off his bodily fetters, and freed his mind from the clay that obscured it, and holds conversation naked with the nakedness of the prime and purest mind . . . ** " (ibid., 18:4).
