Albert Barnes Commentary Amos 5:13

"Therefore he that is prudent shall keep silence in such a time; for it is an evil time." — Amos 5:13 (ASV)

Therefore the prudent shall keep silence in that time - The “time” may be either the time of the obduracy of the wicked, or that of the common punishment. For a time may be called “evil,” whether evil is done, or is suffered in it, as Jacob says, Few and evil have the days of the years of my life been (Genesis 47:9). Of the first, he would perhaps say, that the oppressed poor would, if wise, be silent, not complaining or accusing, for, injustice having the mastery, complaint would only bring on them fresh sufferings. And again also he may mean that, on account of the incorrigibleness of the people, the wise and the prophets would be silent, because the more the people were rebuked, the more impatient and worse they became. So our Lord was silent before His judges, as had been foretold of Him, for since they would not hear, His speaking would only increase their condemnation.

If I tell you, you will not believe; and if I also ask you, you will not answer Me, nor let Me go (Luke 22:67–68). So God said by Solomon: He that reproves a scorner gets himself shame, and he that rebukes a wicked man gets himself a blot (Proverbs 9:7). And our Lord bids, Give not that which is holy to dogs, and cast not your pearls before swine (Matthew 7:6). They hated and rejected those who rebuked them (Matthew 7:10). Since then rebuke did not profit, the prophets should hold their peace. It is a fearful judgment, when God withholds His warnings.

In times of punishment also the prudent keep silence. Intense affliction is dumb and does not open its mouth, owning the hand of God. It may be too, that Amos, like Hosea (Hosea 4:4, Hosea 4:17), expresses the uselessness of all reproof, in regard to most of those whom he called to repentance, even while he continued earnestly to rebuke them.