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To avoid dissensions we should ever be on our guard, more especially with those who drive us to argue with them, with those who vex and irritate us, and who say things likely to excite us to anger. When we find ourselves in company with quarrelsome, eccentric individuals, people who openly and unblushingly say the most shocking things, difficult to put up with, we should take refuge in silence, and the wisest plan is not to reply to people whose behavior is so preposterous.
Those who insult us and treat us contumeliously are anxious for a spiteful and sarcastic reply: the silence we then affect disheartens them, and they cannot avoid showing their vexation; they do all they can to provoke us and to elicit a reply, but the best way to baffle them is to say nothing, refuse to argue with them, and to leave them to chew the cud of their hasty anger. This method of bringing down their pride disarms them, and shows them plainly that we slight and despise them.

[Sed etiam ille cavendus; est, qui videri potest, quicumque inritat, quicumque incitat, quicumque exasperat, quicumque incentiva luxuriae aut libidinis suggerit. Quando ergo aliquis nobis convitiatur, lacessit, ad violentiam provocat, ad iurgium vocat: tunc silentium exerceamus, tunc muti fieri non erubescamus. Peccator est enim qui nos provocat, qui iniuriam facit et nos similes sui fieri desiderat.
Denique si taceas, si dissimules, solet dicere: Quid taces? Loquere, si audes; sed non audes, mutus es, elinguem te feci. Si ergo taceas, plus rumpitur; victum sese putat, inrisum, posthabitum atque inlusum.]

Ambrose of Milan (339-397) Roman theologian, statesman, Christian prelate, saint, Doctor of the Church [Aurelius Ambrosius]

De Officiis Ministrorum [On the Duties of the Clergy], Book 1, ch. 5, sec. 17-18 (AD 386)
    (Source)

(Source (Latin)). Other translation:

But he also is to be shunned which is visible whosoever he be that provoketh, whosoever he be that inciteth, whosoever he be that exaspereth, whosoever he be that giveth the first breath, that suggesteth the first blast to kindle the coales to luxurie, and lustfulnesse. When some one therefore doth raile at us, doth vexe, provoke to violence, stirre up to wrath, then let us exercise silence; then let us not be ashamed to be dumbe.
For hee is a very sinfull wretch, that provoking, that offering injurie is desirous therein to make us like himselfe. To shut up the matter if thou holdest thy peace, if thou seemest not to regard whatsoever he speakes, he is wont to say, why art thou mute? speake if thou darest? but thou darest not, thou art put to a non-plus, I have made thee lose thy tongue; If therefore thou be silent he is more molested, and ready to breake with anger, because he thinkes himselfe overcome, skorned, deluded, and contemned.
[tr. Humfrey (1637)]