What is the ruling on sitting with one's parents when there is something objectionable present?

The rights of parents are great, and being dutiful to them is among the most obligatory duties and greatest acts of devotion. Their rights do not diminish if they commit sins, for Allah has commanded us to accompany them with kindness, even if they are polytheists. However, it is not permissible to sit with them while they are committing evil. If the child can avoid the evil and not participate with them in it while sitting with them, then it is permissible for him to sit with them while avoiding the evil.