There are two things in people that are signs of disbelief: defaming lineages and wailing over the dead

Explanation

The Prophet (may Allah's peace and blessings be upon him) informs of two traits in people that are from the disbelievers' practices and from the morals of Jāhiliyyah (the pre-Islamic era of ignorance), which are: First: Defaming people's lineages, belittling them, and treating them arrogantly. Second: Raising the voice when a calamity strikes by way of expressing resentment at the divine decree or tearing clothes out of extreme discontent.

Benefits

• Encouraging Muslims to be modest and to refrain from treating people with arrogance.
• It is obligatory to deal patiently with calamities and to avoid discontentment.
• These deeds are from the minor Kufr (disbelief), and one who possesses any of the traits of Kufr is not a disbeliever, the commission of which leads to apostasy unless he commits major Kufr.
• Islam forbids whatever leads to dissension among Muslims like defaming lineages and others.