Qadr is belief that Allah knows all things and has decreed them, good and bad, and that nothing happens outside his knowledge. The Hebrew Bible and the Gospels teach the same sovereignty: God directs a person’s steps, his life is written in his book, and a believer says “if the Lord will”.
What it is in Islam
The Quran says all things were created by measure and written in a register, and the hadith of Jibril names the decree as the sixth article of faith.
“Indeed, all things We created with predestination.”
“No disaster strikes upon the earth or among yourselves except that it is in a register before We bring it into being - indeed that, for Allah, is easy -”
“Say, ‘Never will we be struck except by what Allah has decreed for us; He is our protector.’ And upon Allah let the believers rely.”
“And it is not [possible] for one to die except by permission of Allah at a decree determined. And whoever desires the reward of this world - We will give him thereof; and whoever desires the reward of the Hereafter - We will give him thereof. And we will reward the grateful.”
“And never say of anything, ‘Indeed, I will do that tomorrow,’ Except [when adding], ‘If Allah wills.’”
“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.”
Narrated by Umar ibn al-Khattab. English as shown on sunnah.com.
“Then Allah sends an angel who is ordered to write four things. He is ordered to write down his (i.e. the new creature’s) deeds, his livelihood, his (date of) death, and whether he will be blessed or wretched (in religion).”
Narrated by Abdullah bin Mas‘ud. English as shown on sunnah.com.
In the earlier scriptures
Passages are the King James Version unless marked otherwise. Each carries a tag: a close parallel, a shared principle, or an interpretation (Muslim or traditional), which is a reading we offer as a reading and not as a proven fact.
“A man’s heart deviseth his way: but the LORD directeth his steps.”
A person plans, but God directs his steps.
“The lot is cast into the lap; but the whole disposing thereof is of the LORD.”
Even the casting of a lot is disposed of by the Lord.
“Declaring the end from the beginning, and from ancient times the things that are not yet done, saying, My counsel shall stand, and I will do all my pleasure:”
God declares the end from the beginning. Compare Quran 57:22: it is in a register before He brings it into being.
“Seeing his days are determined, the number of his months are with thee, thou hast appointed his bounds that he cannot pass;”
A person’s days are determined and he cannot pass the bounds God set. Compare Quran 3:145: death comes “at a decree determined”.
“Thine eyes did see my substance, yet being unperfect; and in thy book all my members were written, which in continuance were fashioned, when as yet there was none of them.”
The psalmist says that all his members were written in God’s book before any of them existed.
“Are not two sparrows sold for a farthing? and one of them shall not fall on the ground without your Father. But the very hairs of your head are all numbered.”
Not a sparrow falls without the Father, and the hairs of the head are numbered.
“For that ye ought to say, If the Lord will, we shall live, and do this, or that.”
“If the Lord will.” The Quran teaches the same phrase for any plan (18:23–24).
Where this page stands: God’s sovereignty over what happens is shared in plain words. Questions of human choice and accountability are argued among Muslims and among Christians and Jews, and this page does not settle them.
Sources
Quran (Sahih International, via api.alquran.cloud; links go to quran.com)
Hadith (English from sunnah.com)
Hebrew Bible and New Testament (King James Version, text via bible-api.com; links go to BibleGateway)