What is the legal ruling on the Imam's recitation in which he begins by omitting the first letters or words of verses, such as omitting "Qul" (Say) from "Qul id'u Allah" (Say: Call upon Allah) and reciting "id'u Allah" (Call upon Allah), or omitting "Wa" (And) from "Wa laqad arsalna Nuh[an]" (And indeed, We sent Noah) and reciting "laqad arsalna Nuh[an]" (Indeed, We sent Noah)?

A Muslim is not permitted to intentionally omit or add a letter to the Book of Allah. Whoever does so intentionally is a sinner. Al-Shanqeeti narrated from Qadi Iyad that whoever does so intentionally has committed an act of disbelief (kufr). What the questioner heard from the Imam might have been a slip of the tongue, an error, or a misunderstanding by the listener, and it is inconceivable that the Imam would intentionally alter the Quran. If the error or oversight is in a part other than Al-Fatihah, it does not affect the validity of the prayer.