What does 'Kallā sayaʿlamūn' mean in Surah An-Naba 78:4-5?
Answer
In Surah An-Naba 78:4-5, 'Kallā sayaʿlamūn' (كَلَّا سَيَعْلَمُونَ) means 'No indeed; they will come to know,' followed in verse 5 by 'Thumma kallā sayaʿlamūn' — 'Again, no indeed; they will come to know.' The word 'Kallā' is a sharp Arabic particle of rebuke and deterrence, here rebutting those who disputed and doubted the resurrection raised in the opening verses (78:1-3, 'the great announcement about which they differ'). The phrase 'sayaʿlamūn' ('they will come to know') is a veiled but severe threat: those who reject the Day of Judgment will inevitably learn the truth of it when its terrors and consequences befall them. Classical exegetes including al-Saʿdī, al-Ṭabarī, Ibn Kathīr, and al-Qurṭubī explain that the second verse repeats the warning with 'Thumma' ('then/again') for emphasis and intensification — doubling the certainty of the coming reckoning so the deniers cannot dismiss it. The structure leaves the object of their future knowledge deliberately unstated, which heightens the dread: they will come to know something so grave it needs no naming. But notice the exact shape of the threat. It is not 'they will be destroyed' or 'it is over for them'; it is 'they will come to know' — and knowledge is the one thing every honest heart is built to want. The warning, read closely, hands you the way past it. The deniers will know on the Day whether they wanted to or not, when the cover is pulled back and sight turns sharp too late (50:22); but nothing stops you from coming to know today, while knowing is still a door and not yet a verdict. The same God who lets the future tense hang over the deniers is the One quietly inviting you to step out of that 'they' — to know now, willingly, before knowing arrives as regret.
Qur’anic evidence — read the full study of 78:4 →
In more depth
There is a hidden mercy in why the future tense is used at all. To say 'they will come to know' is to admit that, for now, they do not — and that the not-knowing is not yet the end of the story. The Qur'an pairs almost every warning with this gap of time, and the gap is the room God leaves for return. Al-Ṭabarī and al-Qurṭubī note a second reading in which the first 'they will come to know' is the warning to the deniers and the second the believers' reward — dread and joy sitting inside the same words; the stronger reading takes both as escalating warnings, yet even then the warning is aimed at a refusal not yet sealed in anyone still able to hear it. Hold onto why that gap exists at all. It is not an oversight in the threat — it is the signature of the One who made it. The same God whose justice guarantees that everyone will one day know is the God who, for now, withholds the verdict so that you might come to Him before it falls. And something in you already half-knows what these verses point to — the quiet certainty that you were made for more than this brief life, that a reckoning is fitting, that the announcement you keep hearing about is real. That recognition is the fitra, the knowing God placed in you before any argument reached you. 'Sayaʿlamūn' promises the truth will one day be undeniable to everyone; the mercy is that it need not wait for that Day to become undeniable to you. Turn toward Him now, and do not despair of His mercy (39:53) — He set the warning on your path precisely so you would never have to learn it the other way.