Surah Muhammad 47:20

وَيَقُولُ ٱلَّذِينَ ءَامَنُوا۟ لَوْلَا نُزِّلَتْ سُورَةٌ ۖ فَإِذَآ أُنزِلَتْ سُورَةٌ مُّحْكَمَةٌ وَذُكِرَ فِيهَا ٱلْقِتَالُ ۙ رَأَيْتَ ٱلَّذِينَ فِى قُلُوبِهِم مَّرَضٌ يَنظُرُونَ إِلَيْكَ نَظَرَ ٱلْمَغْشِىِّ عَلَيْهِ مِنَ ٱلْمَوْتِ ۖ فَأَوْلَىٰ لَهُمْ

Those who believe say, "Why has a sūrah not been sent down?" But when a precise sūrah is revealed and battle is mentioned therein, you see those in whose hearts is disease [i.e., hypocrisy] looking at you with a look of one overcome by death. And more appropriate for them [would have been]

Translation: Saheeh International

Tafsir

And those who believe say seeking to take part in the struggle ‘Why has a sūra not been revealed?’ one in which there is mention of the command to participate in the struggle. …

Excerpt from Tafsir al-Jalalayn, commentary on 47:20, via Quran.com. The reader has the full commentary and 9 more tafsirs.