Evidence for belief in Qadar can be found in the following statements of Allaah, the Most High: “Allaah’s command is a determined decree.” (Soorah al-Ahzaab, 33: 38).
Qadar, coming from the root qadara (evaluate), may be defined as Allaah’s predestination of everything for His creation in accordance with His prior knowledge (Believing in Qadar, p. 8); it is Allaah’s decree or decision as in the verse: “Indeed, I have created all things according to predestined proportions [Qadar].” (Soorah al-Qamar, 54: 49).
Also derived from the same root is the word Qadr (amount) from which Laylatul-Qadr (the night in which Allaah sends down His annual decree and decides the amounts of all things relating to His creation) comes. It is synonymous to Qadar in this context. The Divine Names al-Qaadir (Most Able), al-Qadeer (All-Powerful) and al-Muqtadir (Omnipotent) are all derived from the root.
Qadaa (decision) is the implementation of Allaah’s decree (Al-Mufradaat, p. 406) as in the verse:
“When He decrees a matter, He only says to it: ‘Be!’ – and it is.” (Soorah al-Baqarah, 2: 117).