If the Imaam dispraises or praises someone for whom it is not permissible, will the obligation of listening to the Khutbah be annulled?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Listening to the Khutbah (i.e. Friday sermon) is obligatory. Ibn Qudaamah proved this in Al-Mughni, with the Hadeeth: “If you say to your companion when the Imaam is preaching on Friday, ‘Be quiet and listen,’ you have engaged in idle talk.” [Al-Bukhari and Muslim]

However, this obligation is binding if the Khateeb does not engage in idle and vain talk.

Ibn Habeeb a Maaliki jurist, said: “If the Imaam engages in idle talk in his sermon and speaks about what is not beneficial to the people, then they do not need to listen nor pay attention to him, and this was done by Ibn Al-Musayyab ."