What is the ruling on pronouncing the letter "ẓāʾ" (ظ) in "Astaghfirullah Al-Aẓīm" (أستغفر الله العظيم) as the letter "sīn" (س), and is this considered disbelief?

"Disbelief is not incurred by a linguistic error resulting from mistake or an inability to pronounce correctly, for Allah says: 'And there is no blame upon you for that in which you have erred, but [there is blame for] what your hearts intended.'

However, it is not permissible for a person to intentionally make an error in the Beautiful Names (of Allah), for that entails distorting the names of Allah, and it is a form of atheism (ilhad) that must be condemned. The names and attributes of Allah are tawqifiyyah (revealed and not subject to human reasoning); they must be pronounced exactly as they appeared in the texts of revelation."