Sirach 27:5
Ben Sira, Ecclesiasticus3 If a person is not steadfast in the fear of the Lord, his house will be quickly overthrown. 4 When a sieve is shaken, the refuse appears; so do a person's faults when he speaks. 5 The kiln tests the potter's vessels; so the test of a person is in his conversation. 6 Its fruit discloses the cultivation of a tree; so a person's speech discloses the cultivation of his mind. 7 Do not praise anyone before he speaks, for this is the way people are tested.
Augustine City of God 21.26
On the City of God Against the PagansWould you hear, in the apostle's own words, who he is who builds on the foundation gold, silver, precious stones? He that is unmarried, he says, cares for the things that belong to the Lord, how he may please the Lord. Would you hear who he is that builds wood, hay, stubble? But he that is married cares for the things that are of the world, how he may please his wife. Every man's work shall be made manifest: for the day shall declare it,— the day, no doubt, of tribulation — because, says he, it shall be revealed by fire. He calls tribulation fire, just as it is elsewhere said, The furnace proves the vessels of the potter, and the trial of affliction righteous men.
Notes and References
"... As to Augustine’s use of the Book of Ecclesiasticus, it is striking that more than once he quotes a text that is somewhat different from the Vetus Latina, which for the Book of Ben Sira, serves as the traditional Latin text. Since Augustine’s quotations from the Book of Ben Sira have more than once been brought in line with the Greek translation, a thorough investigation into this phenomenon is needed in order to find out whether he had (some) knowledge of the Greek text of the Book of Ecclesiasticus. Apart from Speculum in which Augustine for his quotations from the Book of Ben Sira usually follows the Latin, in his other works he rather frequently appears to correct the Latin Ben Sira quotations according to the Greek. An investigation into this intriguing question would be very useful. Such an in depth inquiry should also take into full consideration whether, and to what extent, St. Augustine has been influenced by a text type of Ecclesiasticus that was already used by St. Cyprian and has even been given its own siglum (K) by Thiele ..."
Beentjes, Pancratius C. "Saint Augustine's Sermons 38-41 on the Book of Ben Sira" in Menken, M.J.J. (ed.) The Scriptures of Israel in Jewish and Christian Tradition: Essays in Honour of Maarten J.J. Menken (pp. 81-94) Brill, 2013