Sirach 27:4-7
27:4 When a sieve is shaken, the refuse appears; so do a person's faults when he speaks.

27:5 The kiln tests the potter's vessels; so the test of a person is in his conversation.

27:6 Its fruit discloses the cultivation of a tree; so a person's speech discloses the cultivation of his mind.

27:7 Do not praise anyone before he speaks, for this is the way people are tested.