What is the ruling on saying "wa-llāhi al-ʿazīm" (By God, the Determined/Resolute) instead of "wa-llāhi al-ʿaẓīm" (By God, the Most Great), and is this statement unlawful and to be condemned?

Deliberately substituting the letter "Dhaa" (ظ) with "Zay" (ز) in Allah's name "Al-Atheem" (العظيم) is impermissible, as it constitutes a distortion of Allah's Most Beautiful Names and a form of atheism concerning them. The Names and Attributes of Allah must be pronounced exactly as they were revealed in the sacred texts. However, one who makes a mistake or is unable to pronounce the "Dhaa" is not sinful, for Allah says: "And there is no blame upon you for that in which you have erred, but [only for] what your hearts intended."