תהלים, פרק נ׳, פסוק כ׳

A person's moral decline reaches a low point when they join with others simply to slander their closest relatives. The primary approach among commentators is that this refers to joining a gathering of cynics, a social circle dedicated entirely to idle talk and gossip. This behavior does not happen overnight but is the result of a gradual process [אבן עזרא]. A person might begin by harming strangers and people outside their immediate circle. Over time, however, this negative habit grows until they are perfectly comfortable sitting down to speak poorly even about their own family.

The severity of this betrayal is highlighted by focusing on the victim's identity as both a brother and a mother's son. While a brother might refer to a sibling from the same father, specifying a mother's son points to the most certain and intimate family bond possible [מצודת דוד]. Attacking a maternal brother is considered especially cruel and illogical. Because maternal brothers do not share a father's inheritance, there is no financial or legal ground for conflict between them. Therefore, hating and slandering such a close relative is completely unjustified [רש״י, רד״ק].

The actual words spoken in these gatherings are understood by most commentators as expressions of deep disgrace, insult, and abuse. There is also an additional layer of meaning suggesting that these insults are specifically designed to push away and socially reject the person being targeted [רש״י]. The goal of the gossip is not just to speak badly, but to actively distance the victim from the community.

Beyond the realm of human relationships, a Midrashic tradition applies these ideas to the relationship between a person and God's teachings [תורה תמימה]. This tradition points to King Manasseh of Judah, who would sit and interpret the teachings of the Torah with open mockery and insult. In response to his blatant disrespect, a heavenly voice rebuked him. The voice compared his cynical mockery of God's word to the unnatural and cruel act of publicly attacking one's own brother and mother's son.