زَعَمَ ٱلَّذِينَ كَفَرُوٓا۟ أَن لَّن يُبْعَثُوا۟ ۚ قُلْ بَلَىٰ وَرَبِّى لَتُبْعَثُنَّ ثُمَّ لَتُنَبَّؤُنَّ بِمَا عَمِلْتُمْ ۚ وَذَٰلِكَ عَلَى ٱللَّهِ يَسِيرٌ
Za'amal lazeena kafarooo al-lany yub'asoo; qul balaa wa rabbee latub'asunna summa latunabba'unna bimaa 'amiltum; wa zaalika 'alal laahi yaseer
The disbelievers claim they will not be raised from the dead. Say [Prophet], ‘Yes indeed! I swear by my Lord! You will be raised and then you will be informed about everything you have done: an easy matter for God.’
Those who deny claim they will never be raised again. Say: yes indeed, by my Lord, you will surely be raised, and then you will be informed of what you did. That is easy for God.
Zaʿama is Arabic's verb for an assertion put forward without evidence, so the denial is named a claim before any answer to it begins. The answer rests on balā, a particle that contradicts a negative statement and affirms what it denied, which English can only spread across two or three words. The Prophet is instructed to swear by his Lord in three places in the Qur'an, and all three answer the same doubt about what comes after death.