What is the ruling on praying behind an Imam who recites according to the Warsh narration, and errs in his recitation of "Maliki Yawm Ad-Din" (Master of the Day of Judgment) by saying "Milki Yawm Ad-Din" (Possession of the Day of Judgment), thereby changing the meaning, and does this affect the validity of the prayer?

The Imam's lengthening of the kasra in "Maliki" (ملك) to pronounce it as "Maleeki" (ملكي) is narrated from some scholars, such as Ibn Kathir, and it is a dialect of the Arabs. Therefore, the prayer is not invalidated by it. Even if it were considered a grammatical error (laḥn), the Malikis do not consider the prayer invalid due to an unintentional grammatical error in Al-Fatiha. Thus, praying behind him is valid, and he should be advised gently and wisely to avoid that, because Warsh (a reciter) does not lengthen the kasra in this word.