All praise is due to Allah The Exalted, and may Allah raise the rank of our beloved Prophet Muhammad peace be upon him, his kind relatives and companions, and protect his nation from that which he feared for them thereafter;
Believing in al-Qadar is among the fundamental basics of the Islamic creed. The one who denies al-Qadar is a blasphemer. The definition of al-Qadar is the managing of things so they occur in compliance with the Eternal Knowledge of Allah and His Eternal Will.
Al-Qadar has also another meaning which is al-maqdur (i.e. the created things that exist by the predestination of Allah). According to the second meaning, it includes both good and evil. All the good and bad deeds of a slave occur by the Will of Allah. Both good and evil are part of this universe and thus they occur by al-Qadar of Allah ta^ala.
This is clarified by the hadith narrated by Muslim in which the Prophet answered Jibril when he asked him about the correct belief. The Prophet said: “The proper belief is to believe in Allah ta^ala, His angels, His revealed books, His prophets and messengers, the Day of Judgment, and to believe in al-Qadar both good and evil“.
Al-Bayhaqiyy narrated that our master ^Aliyy said: “No one amongst you would have the proper belief in his heart unless one firmly believes without any doubt that whatever happens to one, had not been predestined to miss one, and whatever misses one, had not been predestined to happen to one. One must believe that al-Qadar encompasses all the creations”. Thus, it is blasphemous to believe that only part of the creations are encompassed by al-Qadar while other creations are not.
Allah ta^ala said in Suratul-Furqan, Ayah 2:
وَخَلَقَ كُلَّ شَىء
which means: [And He created everything.] The universe in its entirety is a creation of Allah ta^ala. He, subhanahu wa ta^ala, is the Manager of everything. He is the One Who makes things run according to His eternal Will and Knowledge. Hence, nothing happens in the entire universe except by His management.
Al-Bayhaqiyy related that the Prophet, sallallahu ^alayhi wa sallam, said: “O Allah, the One Who controls the hearts, guide our hearts to obey to You“.
Allah, ta^ala, said in Suratuz-Zumar, Ayah 62:
اللهُ خَالِقُ كُلِ شَىء
which means: “Allah is the Creator of everything“.
The Will of Allah does not change because change occurs in creatures, and change is the most significant sign of being a creation. Allah ta^ala said in Surat Qaf, Ayah 29:
مَا يُبَدَّلُ القَوْلُ لَدَيّ
which means: “That which I have decreed does not change“.
Imam Muslim related that the Messenger of Allah, sallallahu ^alayhi wa sallam, said: << Allah said the meaning of which is: O Muhammad, if I decreed a matter then it will never be opposed.>> Allah changes the creatures in accordance with His Will that does not change. Whatever He willed to happen shall occur at the time that He willed for it to exist, and that which He did not will for to happen shall never exist.
Abu Dawud related that the Messenger of Allah said: <<Whatever Allah willed to be shall be and whatever Allah did not will to be shall not be.>> Good and evil, obedience and sinning, and blasphemy and belief all of that occur by the Will of Allah, His Knowledge, Decree, and Creating. However, the good is accepted and ordered by Allah and evil is not accepted or ordered by Him.
And Allah knows best