8) In the warning "Do not stand idly by the blood of your neighbor," it means that even by merely standing idly without responding, you should not witness your friend's distress when someone humiliates him or speaks ill of him. Instead, you should do everything in your power to rebuke the one who belittles your friend or engages in gossip and evil speech. You should not be a listener and remain silent.
Rather, you should say to him, "Evil one, you are troubling Israel. Why do you speak slander against the image of our Creator and the Divine presence that is within your people, and thereby incur this sin?" And for this reason, one prohibition is linked to the other: "Do not go about as a talebearer" and "Do not stand idly by the blood of your neighbor." This means that if I refrain from speaking, thinking that I will listen quietly and derive pleasure from hearing what the wicked person says about my friend, even the one who listens and remains silent is considered utterly wicked.
Such a person transgresses the commandment of not standing idly by the blood of their neighbor. Such a person has no share in the God of Israel when they listen to the wicked speaking slander against the righteous or engage in whispering lies about their friend. Rather, immediately reject them and say to them, "Wicked one, depart from me, I will not listen to you." If someone merely listens and remains silent, they are certainly condemned to an unquenchable fire and will not merit to stand among the partition of the righteous. When listening, responding, speaking, they will all ultimately perish from the world because of this and similar sins.