What is Qadr (divine decree, predestination) in Islam?

The belief in Qadr, predestination, is that Allah ordained everything before its occurrence and recorded it in the Preserved Tablet. Belief in Qadr is one of the six articles of faith.

Allah's Messenger ﷺ said, "Allah ordained the measures (of quality) of the creation fifty thousand years before He created the heavens and the earth, as His Throne was upon water." [Sahih Muslim 2653]

Belief in Qadr is the firm attestation to the fact that all general and particular decrees have been pre-recorded, and that Allah has created everything and assigned it a proper measure. As the Qur'an mentions: "Verily, We have created everything by a decree." [Qur'an, al-Qamar 54:49]

As Muslims, we believe that Allah is well acquainted and His knowledge encompasses everything. The Qur'an mentions: "Do you not know that Allah knows whatever is in the heavens and the earth? Surely, it is all preserved in a record, and that is easy for Allah." [Qur'an, al-Hajj 22:70]

Nothing takes place in the heavens or on earth without the will of Allah: "Verily, His command, when He wants a thing, is only that He says to it, 'Be'! And it is." [Qur'an, Ya-Sin 36:82]

Everything is assigned and preserved in the Tablet, as the Qur'an mentions: "There is nothing, which takes place on earth, or in you, but is foreordained before We brought it into existence." [Qur'an, al-Hadid 57:22]