Sirach 27:5

5 The furnace proveth the potter's vessels; so the trial of man is in his reasoning.

Sirach 27:5 In-Context

3 Unless a man hold himself diligently in the fear of the Lord, his house shall soon be overthrown.
4 As when one sifteth with a sieve, the refuse remaineth; so the filth of man in his talk.
5 The furnace proveth the potter's vessels; so the trial of man is in his reasoning.
6 The fruit declareth if the tree have been dressed; so is the utterance of a conceit in the heart of man.
7 Praise no man before thou hearest him speak; for this is the trial of men.

The Brenton translation of the Septuagint is in the public domain.