The Permanent Committee was asked:
What is the ruling on praying behind a Shi’ee (Raafidi)?
“Prayer behind an innovator whose innovation is one that expels an individual from the religion is not valid. That is like one who seeks refugee with other than Allah or calls to other than Allah or slaughters for other than Allah or believes the Quran is deficient or defames the honor of the Mother of the Believers Aisha (may Allah be pleased with her) or has extremism in Ali (may Allah be pleased with him) or other than him from the Ahlul Bayt, or calls upon other than Allah or insults the Companions (may Allah be pleased with them).
With Allah is Tawfeeq and may peace and blessings be upon our Prophet (ﷺ), his followers, and all his Companions”.
[Fatwa no. 19479]
Faisal Ibn Abdul Qaadir Ibn Hassan