St. John Chrysostom
“Now as this (the Eucharist) is a great and wonderful thing, so if you approach it with pureness, you approach for salvation; but if with an evil conscience, for punishment and vengeance. For, It says, he that eats and drinks unworthily of the Lord, eats and drinks judgment to himself; since if they who defile the kingly purple are punished equally with those who rend it, it is not unreasonable that they who receive the Body with unclean thoughts should suffer the same punishment as those who rent it with the nails.”
Source: St. John Chrysostom, Homily 46