Slander: Forbidden
Source: TTT
Exodus 23:1
“You shall not spread a false report. Do not join the wicked by being a malicious witness.
Ephesians 4:31
Get rid of all bitterness, rage and anger, outcry and slander, along with every form of malice.
James 4:11
Brothers, do not slander one another. Anyone who speaks against his brother or judges him speaks against the law and judges it. And if you judge the law, you are not a practitioner of the law, but a judge of it.