Hebrews 13:11-13
4 “For the bodies of those beasts whose blood is brought into the sanctuary by the High Priest for sin, are burned without the camp. Wherefore Jesus also, that He might sanctify the people with His own blood, suffered” (he says) “without the gate.” Do you see the type shining forth? “For sin,” he says, and “suffered without the gate.” “Let us go forth therefore to Him without the camp, bearing His reproach,” that is, suffering the same things; having communion with Him in His sufferings. He was crucified without as a condemned person: neither let us then be ashamed to “go forth out” [of the world].
Source: Homilies on the Epistle to the Hebrews (New Advent)