In short, you must never say, “O Allah, forgive me if You will; O Allah, have mercy on me if You will; O Allah, admit me to Paradise if You will; O Allah, grant me children if You will; O Allah, bless me with a righteous wife if You will.” None of this is permissible. Be decisive in what you ask and leave out all conditional wording.
The same ruling applies to another formula some people—whom I suspect belong to certain Sufi circles—repeat: “O Allah, I do not ask You to avert the decree; rather, I ask You for gentleness within it.” This too is forbidden. Why would you not beg Allah to turn the decree away? And what is it that repels the decree except supplication? As the hadith says, “Nothing averts the Divine decree except supplication.” When you utter the phrase “I do not ask You to avert the decree, but only for gentleness within it,” it is as though you are saying, “My Lord, punish me, but be gentle; destroy my loved ones, but be gentle,” and the like.
In all supplications a person must confine himself to what is found in the Book and the Sunnah, or what clearly carries their same meaning. It is not acceptable to adopt a prayer simply because its rhythm or rhyme sounds pleasing.
Thus we now have two issues:
- Do not say, “O Allah, forgive me if You will; O Allah, have mercy on me if You will; O Allah, provide for me if You will; O Allah, guide me if You will.” Make your plea outright and omit the phrase “if You will.”
- Do not say, “O Allah, I do not ask You to avert the decree, but I ask You for gentleness within it.” Rather say, “O Allah, treat me gently; O Allah, spare me from evil,” and the like.
As for the Messenger of Allah ﷺ saying to a sick person, “No harm; it will be a purification, God willing,” this was an expression of hope—a statement, not a direct address to Allah. He did not say “if You will,” but “God willing,” and wording that speaks about Allah rather than speaking to Him is far lighter in import than wording that addresses Him directly. And Allah knows best.