Speak no evil
Then said Paul, I wist not, brethren, that he was the high priest: for it is written, Thou shalt not speak evil of the ruler of thy people. Acts 23:5
Paul said something similar later on to Titus. It is this: we are to "speak evil of no man" (Tit. 3:2). Interestingly enough, it comes right on the heels of a command to obey the authorities (Tit. 3:1). In the charged political climate of our day, it is easy to forget this. Of course there is nothing wrong if we are in disagreement with others, especially with those who are in positions of leadership in our government. But we should beware that believing our cause is the righteous one gives us the right to say whatever we will about those in the government.
Now someone might argue that the text Paul is quoting is about the leaders of God's people. Okay. But we must never forget that the powers that be are ordained of God (Rom. 13:1). Just because they happen to belong to the other political party doesn't give us the right to speak evil of them. Nor does the fact that they have done wrong, unjust, or even evil things give us the right to do so - the man Paul was referring to, the high priest Ananias, after all, was responsible for the crucifixion of the Son of God!
Why should we obey this? For the following simple and plain reason: God commanded it! Guard your speech. Remember that by your words you will be justified and by your words you will be condemned (Mt. 12:37). Let us be known, not for the vitriol of our speech, but as gentle, gracious, and God-fearing people.