Quran 9:81 At-Tawbah, ayah 81 of 129

فَرِحَ ٱلْمُخَلَّفُونَ بِمَقْعَدِهِمْ خِلَـٰفَ رَسُولِ ٱللَّهِ وَكَرِهُوٓا۟ أَن يُجَـٰهِدُوا۟ بِأَمْوَٰلِهِمْ وَأَنفُسِهِمْ فِى سَبِيلِ ٱللَّهِ وَقَالُوا۟ لَا تَنفِرُوا۟ فِى ٱلْحَرِّ ۗ قُلْ نَارُ جَهَنَّمَ أَشَدُّ حَرًّا ۚ لَّوْ كَانُوا۟ يَفْقَهُونَ ۝٨١

9:81 Those who were left behind rejoiced at sitting still behind the messenger of Allah, and were averse to striving with their wealth and their lives in Allah's way. And they said: Go not forth in the heat! Say: The fire of hell is more intense of heat, if they but understood.