Isaiah 63:2

Wherefore art thou red in thy apparel
Christ having satisfied the church as to her first question, concerning his person, who he was; she puts a second to him, about the colour of his garments, which was red, and the reason of it. His garments at his transfiguration were white as snow, whiter than any fuller on earth could whiten them; his robe of righteousness is fine linen, clean and white; the garment of his human nature, or his form as man, was white and ruddy; but this, through his bloody sufferings, became red, being all over bloody through the scourges he received, the crown of thorns he wore, the piercing of his hands, feet, and sides, with the nails and spear; but here it appears of this colour not with his own blood, but with the blood of his enemies, as is hereafter explained: and thy garments like him that treadeth in the winefat?
or winepress, into which clusters of grapes are cast, and these are trodden by men, the juice of which sparkles on their garments, and stains them, so that they become of a red colour.