What is the ruling on praying behind an Imam who said: "Were it not for this profession of mine, I would not have prayed with you, and when I retire, perhaps I will not pray at all when I remember some of the worshipers; then, if He wills, He will forgive me, and if He wills, He will not forgive me"?

It is probable that the Imam's words were a result of anger and mistreatment, and while they are ugly words, they do not constitute disbelief (kufr). He must repent to Allah. However, if his intention was to mock the religion, then that is disbelief which expels one from the fold of Islam. It is not permissible to boycott the mosque, as congregational prayer is obligatory and is twenty-seven degrees superior to individual prayer.