Sirach 20:7
Ben Sira, Ecclesiasticus1 There is a rebuke that is untimely, and there is the person who is wise enough to keep silent. 2 How much better it is to rebuke than to fume! 3 And the one who admits his fault will be kept from failure. 4 Like a eunuch lusting to violate a girl is the person who does right under compulsion. 5 Some people keep silent and are thought to be wise, while others are detested for being talkative. 6 Some people keep silent because they have nothing to say, while others keep silent because they know when to speak. 7 The wise remain silent until the right moment, but a boasting fool misses the right moment. 8 Whoever talks too much is detested, and whoever pretends to authority is hated.
Ambrose On the Duty of the Clergy 1.5
5 Now what ought we to learn before everything else, but to be silent, that we may be able to speak? Lest my voice should condemn me, before that of another acquit me; for it is written: By your words you shall be condemned. What need is there, then, that you should hasten to undergo the danger of condemnation by speaking, when you can be more safe by keeping silent? How many have I seen to fall into sin by speaking, but scarcely one by keeping silent; and so it is more difficult to know how to keep silent than how to speak. I know that most persons speak because they do not know how to keep silent. It is seldom that any one is silent even when speaking profits him nothing. He is wise, then, who knows how to keep silent. Lastly, the Wisdom of God said: The Lord has given to me the tongue of learning, that I should know when it is good to speak. Justly, then, is he wise who has received of the Lord to know when he ought to speak. Wherefore the Scripture says well: A wise man will keep silence until there is opportunity.
Notes and References
"... The Book of Ecclesiasticus [Sirach] has been honored still more highly among the Christians, being cited in the Epistle of James (Edersheim, in Wace, 'Apocrypha,' p. 21), the Didache (4:5), and the Epistle of Barnabas (19:9), while Clement of Alexandria and Origen quote from it repeatedly, as from a γραφή, or holy book. In the Western Church, Cyprian frequently appeals to it in his 'Testimonia,' as does Ambrose in the greater number of his writings. In like manner the Catalogue of Cheltenham, Damasus I., the Councils of Hippo (393) and Carthage (397), Pope Innocent I., the second Council of Carthage (419), and Augustine all regard it as a canonical book. This is contrary, however, to the opinions of the Council of Laodicea, of Jerome, and of Rufinus of Aquileia, which authorities rank it among the ecclesiastical books. It was finally declared canonical by the Council of Trent; and the favor with which the Church has always regarded it has preserved it in its entirety. ..."
Toy, Crawford Howell The Wisdom of Jesus the Son of Sirach (pp. 1-10) Jewish Encyclopedia, 2021