Jamieson, Fausset and Brown on Amos 5:13

13. the prudent--the spiritually wise.

shall keep silence--not mere silence of tongue, but the prudent shall keep himself quiet from taking part in any public or private affairs which he can avoid: as it is "an evil time," and one in which all law is set at naught. Ep 5:16 refers to this. Instead of impatiently agitating against irremediable evils, the godly wise will not cast pearls before swine, who would trample these, and rend the offerers (Mt 7:6), but will patiently wait for God's time of deliverance in silent submission (Psa 39:9).