Is it permissible to say, "If God wills"?

If the person's intent is to prohibit saying "Insha'Allah" (if Allah wills) in a supplication, then their statement is correct, as there is a prohibition against making exceptions in supplication, such as "O Allah, forgive me if You will." However, if their intent is to prohibit it absolutely, then their statement is incorrect; rather, it is recommended to say it, as in the verse: {And never say of anything, "Indeed, I will do that tomorrow," except [add], "If Allah wills."} (Quran 18:23-24). And whoever speaks concerning the Sharia of Allah must have a basis [for their statement] or know of scholars who have said it.