Tertullian, 2nd CenturyAt every forward step and movement, at every going in and out, when we put on our our clothes and shoes, when we bathe, when we sit at table, when we light the lamps, on couch, on seat, in all the ordinary actions of daily life, we trace upon the forehead the sign.
Delivered on the Second Sunday of Lent 2015 at the Cathedral Church of Saint Luke in Orlando Florida.
Ephraim the Syrian, 4th Century With the sign of the living cross, seal all thy doings, my son. Go not forth from the door of thy house till thou hast signed the cross. Whether in eating or in drinking, whether in sleeping or in waking, whether in thy house or on the road, or again in the season of leisure, neglect not this sign; for there is no guardian like it. It shall be unto thee as a wall, in the forefront of all thy doings. And teach this to thy children, that heedfully they be conformed to it.
Athanasius (from his Life of Saint Anthony), 4th Century But we by the mention of Christ crucified put all demons to flight, whom you fear as if they were gods. Where the sign of the Cross is, magic is weak and witchcraft has no strength.
Cyril Of Jerusalem, 4th Century Let us not then be ashamed to confess the Crucified. Be the Cross our seal made with boldness by our fingers on our brow, and on everything; over the bread we eat, and the cups we drink; in our comings in, and goings out; before our sleep, when we lie down and when we rise up; when we are in the way, and when we are still. Great is that preservative; it is without price, for the sake of the poor; without toil, for the sick; since also its grace is from God. It is the Sign of the faithful, and the dread of devils: for He triumphed over them in it, having made a shew of them openly; for when they see the Cross they are reminded of the Crucified; they are afraid of Him, who bruised the heads of the dragon. Despise not the Seal, because of the freeness of the gift; out for this the rather honour thy Benefactor.
John Chrysostom, 4th-5th Century When therefore thou signest thyself, think of the purpose of the cross, and quench anger, and all the other passions. When thou signest thyself, fill thy forehead with all courage, make thy soul free.
Collect for Holy Cross Day from the Book of Common PrayerAlmighty God, whose Son our Savior Jesus Christ was lifted high upon the cross that he might draw the whole world to himself: Mercifully grant that we, who glory in the mystery of our redemption, may have grace to take up our cross and follow him; who lives and reigns with you and the Holy Spirit, one God, in glory everlasting. Amen.