An evildoer gives heed to wicked lips; and a liar listens to a mischievous tongue. [Proverbs 17:4 AMP]A lie is not only constructed by the telling, but also by the listening; failing to disclose a lie is equivalent to telling the lie itself:
The one who conceals hatred has lying lips. [Proverbs 10:18]The duty of a wise and virtuous man is to counter [quash, inform, disclose] every lie told and heard with responsive [expedient, effective, thorough] action.
There is no small, white or harmless lie, in that there is no harmless sin. Small fires can turn into big ones; responsible people – people who concern themselves with others, as Christ commands – put all of them out, regardless. "Small, white and harmless" are words that disguise the true and hideous nature of evil, and otherwise further its agenda, even if only in small steps; moreover, they reflect your judgment, and not the judgment of God.
In fact, it was man's own judgment in variance to God's followed by a lie that separated man from Him [the rift Christ was sent to close].
In sum, having any role in a lie – whether hearing [failing to disclose, refute] or telling [initiating, relaying, repeating] – you are separating yourself from God, and acting as an agent of the anti-Christ.