I wish to know that if some qari says (daad) as (zaah), is the pronunciation with (zaah) correct? And also wish to know that the prayer is valid behind the imaam who say (daad) as (zaah)?
The place of articulation for the letter ‘zad’ is very similar to the letter of ‘za’, which comes after the letter ‘ta’. And it’s not anywhere near the same as the letter of ‘dal’. If someone intended to pronounce ‘zad’ but he ended up pronouncing ‘dal’ then the prayer would be accepted. But if the intention were to pronounce it than the prayer would be affected.
Original Source Link (from Way Back Machine archive)