What is the view of the Qadariyyah, how can one refute them, and how can one reconcile refuting them with the saying of the Messenger of Allah, peace and blessings be upon him, "Supplicate to Allah while you are certain of a response"?

The Qadariyya are deniers of destiny, who believe that Allah does not know things until they happen. This is a misguided statement, an act of disbelief in Allah, and a denial of the Qur'an and the Sunnah. The correct belief is to affirm Allah's prior knowledge and His recording of the destinies of creations before their creation, and that nothing occurs in His dominion except what He wills and desires, as stated in His saying: "Indeed, We created all things with predestination" (Quran 54:49) and "No disaster strikes upon the earth or among yourselves except that it is in a register before We bring it into being" (Quran 57:22).

Many hadiths from the Prophet (peace be upon him) affirm this, such as "Allah wrote the destinies of creations fifty thousand years before He created the heavens and the earth." The Qadariyya were also described as the Majus (Zoroastrians) of this nation.

The first to speak about Qadar (predestination) was Ma'bad al-Juhani al-Basri, and companions like Ibn Umar disavowed him. Ahlus-Sunnah wal-Jama'ah (the People of the Sunnah and the Community) affirm that humans have choice and will and are held accountable for their actions, but their will is not realized except by Allah's will, as in His saying: "For whoever wills among you to take a straight path. And you do not will except that Allah wills, Lord of the worlds" (Quran 81:28-29).

The statement that supplication (du'a) is useless and that what is beneficial is certainty or will is incorrect. Response [to supplication] is conditioned by certainty and presence of heart, and supplication is a means for acceptance. There is no basis for likening a monotheistic Muslim to an idol worshipper. Justifying sins by destiny is invalid, because the polytheist commits evil by his own choice and is not compelled to do so.