Why does the Sharia encourage supplication when Allah will not answer us, especially after the prohibition against saying, "O Allah, forgive me if You will; O Allah, have mercy on me if You will"?

The supplicant must be firm in his request and not qualify his supplication by saying, "If You wish," as this implies that God is coerced, or that the matter is too great for God, or that the supplicant is independent of God's grace.

Supplication is a great act of worship, and God has commanded it and promised to answer those who supplicate to Him sincerely. However, the answer does not necessarily mean the exact fulfillment of the request; it may be in averting evil or in storing up reward in the Hereafter. Therefore, one should have a good opinion of God and persist in supplication, while observing its manners and avoiding its impediments.