Is it obligatory to sit with neighbors who do not pray, and whose gatherings sometimes involve backbiting?

Being kind to one's neighbor is obligatory, and it is not required to sit with him. A neighbor committing sins, such as backbiting or neglecting prayer, does not negate his rights. However, it is not permissible to sit with him while he is committing a sin. Rather, he should be advised with wisdom and good admonition.