Similarly giving praise out of proportion to someone is a form of lie. Concealing the witness is a form of lying. Hide not the testimony he who hides it, verily his heart is sinful. God is aware of what you do. Concealing the truth is a crime in itself.
Hypocrites are liars, too, because they lie to themselves.
Verily, truth leads to virtue and virtue leads to paradise and a true man continues to speak truth until he becomes the most truthful person. The use of tongue for lying, backbiting, speaking ill, etc. Destruction for him. There are no absolute justifications in Islam and the Prophet has asked us to tell truth even under the harshest circumstances of oppression. He is under oppression and there is danger of losing his life if he told the truth.