41 Wherefore, they which will not do right things, let them give over at least to teach wrong things. Howbeit they be others whom in this speech we reprove: but as for those who by this one fault, of letting their hair contrary to apostolic precept grow long, offend and trouble the Church, because when some being unwilling to think of them any thing amiss are forced to twist the manifest words of the Apostle into a wrong meaning, others choose to defend the sound understanding of the Scriptures rather than fawn upon any men, there arise between the weaker and the stronger brethren most bitter and perilous contentions: which things perchance if they knew, these would correct without hesitation this also, in whom we admire and love all else.
Those then we not reprove, but ask and solemnly beseech by the Godhead and the Manhood of Christ and by the charity of the Holy Ghost, that they no more put this stumbling-block before the weak for whom Christ died, and aggravate the grief and torment of our heart when we bethink us how much more readily evil men can imitate this evil thing for deceiving of mankind, when they see this in them whom on the score of other so great good we with deserved offices of Christian love do honor.
If however, after this admonition, or rather this solemn entreaty of ours, they shall think fit to persevere in the same, we shall do nothing else but only grieve and mourn. This let them know; it is enough. If they be servants of God, they have pity. If they have not pity, I will not say any thing worse. All these things, therefore, in the which perhaps I have been more loquacious than the occupations both of you and of me could wish, if you approve the same, make to be known to our brethren and sons, on whose behalf you have deigned to put this burden upon me: but if anything seem to you meet to be withdrawn or amended, by reply of your Blessedness I shall know the same.
Source: On the Work of Monks (New Advent)