The Salaf's Guide to the Understanding of al-Qadaa' wal Qadar (Fate in Islaam)

Al-Qadar is an Article of faith:

Yahya bin Ya'mur (a famour Tabi'ee and a narrator of Hadeeth) set out on a pilgrimage to Macca along with Humaid b. Abdur Rehman Himyari, and said, "Should we meet one of the Companions of the Messenger of Allaah, we will ask him about Taqdeer (Qadar)." Incidentally they met Abdullah, the son of Umer ibn Khattab ? and said to him, "O Abu Abdar-Rehman, there have appeared in our land who recite the Holy Qur'aan and peruse knowledge…. They claim that there is no such thing as Divine Decree and events are not pre-Destined". He (Abdullah ibn Umer) said, "When you happen to meet such people tell them that I have nothing to do with them and they have nothing to do with me. And verily they are in no way responsible for my (belief)". Abdullah ibn Umar swore by Him (the Lord) (and said): If any one of them (who does not believe in the Divine Decree) had with him gold equal to the bulk of (the mountain) Uhud and then, it (in the way of Allah), Allah would not accept it unless he affirmed his faith in Divine Decree". He further said: My father, Umar ibn al-Khattab, told me: "One day we were sitting in the company of Allah's Messenger (salallahu alaihi wa salalam) when there appeared before us a man dressed in pure white clothes, his hair extraordinarily black….. He (the inquirer) said: Inform me about Eeman (faith). He (the Prophet (salallahu alaihi wa salalam)) replied: That you affirm your faith in Allah, in His angels, in His Books, in His Apostles, in the Day of Judgment, and you affirm your faith in the Divine Decree about good and evil. He (the inquirer) said: You have told the truth." …. After the inquirer left, the Prophet (salallahu alaihi wa salalam) said, "He was Gabriel (the angel). He came to you in order to instruct you in matters of religion."