The Canons of the Council in Trullo; Often Called The Quinisext Council 73Canon LXXIII.

Since the life-giving cross has shewn to us Salvation, we should be careful that we render due honour to that by which we were saved from the ancient fall. Wherefore, in mind, in word, in feeling giving veneration (proskunesin) to it, we command that the figure of the cross, which some have placed on the floor, be entirely removed therefrom, lest the trophy of the victory won for us be desecrated by the trampling under foot of those who walk over it. Therefore those who from this present represent on the pavement the sign of the cross, we decree are to be cut off.