The Repentance
فَلَا تُعْجِبْكَ أَمْوَٰلُهُمْ وَلَآ أَوْلَـٰدُهُمْ ۚ إِنَّمَا يُرِيدُ ٱللَّهُ لِيُعَذِّبَهُم بِهَا فِى ٱلْحَيَوٰةِ ٱلدُّنْيَا وَتَزْهَقَ أَنفُسُهُمْ وَهُمْ كَـٰفِرُونَ
So let not their wealth or their children impress you. Allah only intends to punish them through them in worldly life and that their souls should depart [at death] while they are disbelievers.
Nearby ayahs help place verse 9:55 in sequence and meaning.
قُلْ أَنفِقُوا۟ طَوْعًا أَوْ كَرْهًا لَّن يُتَقَبَّلَ مِنكُمْ ۖ إِنَّكُمْ كُنتُمْ قَوْمًا فَـٰسِقِينَ
Say, "Spend willingly or unwillingly; never will it be accepted from you. Indeed, you have been a defiantly disobedient people."
وَمَا مَنَعَهُمْ أَن تُقْبَلَ مِنْهُمْ نَفَقَـٰتُهُمْ إِلَّآ أَنَّهُمْ كَفَرُوا۟ بِٱللَّهِ وَبِرَسُولِهِۦ وَلَا يَأْتُونَ ٱلصَّلَوٰةَ إِلَّا وَهُمْ كُسَالَىٰ وَلَا يُنفِقُونَ إِلَّا وَهُمْ كَـٰرِهُونَ
And what prevents their expenditures from being accepted from them but that they have disbelieved in Allah and in His Messenger and that they come not to prayer except while they are lazy and that they do not spend except while they are unwilling.
وَيَحْلِفُونَ بِٱللَّهِ إِنَّهُمْ لَمِنكُمْ وَمَا هُم مِّنكُمْ وَلَـٰكِنَّهُمْ قَوْمٌ يَفْرَقُونَ
And they swear by Allah that they are from among you while they are not from among you; but they are a people who are afraid.
لَوْ يَجِدُونَ مَلْجَـًٔا أَوْ مَغَـٰرَٰتٍ أَوْ مُدَّخَلًا لَّوَلَّوْا۟ إِلَيْهِ وَهُمْ يَجْمَحُونَ
If they could find a refuge or some caves or any place to enter [and hide], they would turn to it while they run heedlessly.