At-Tawbah 9:81

فَرِحَ ٱلْمُخَلَّفُونَ بِمَقْعَدِهِمْ خِلَٰفَ رَسُولِ ٱللَّهِ وَكَرِهُوٓا۟ أَن يُجَٰهِدُوا۟ بِأَمْوَٰلِهِمْ وَأَنفُسِهِمْ فِى سَبِيلِ ٱللَّهِ وَقَالُوا۟ لَا تَنفِرُوا۟ فِى ٱلْحَرِّ ۗ قُلْ نَارُ جَهَنَّمَ أَشَدُّ حَرًّۭا ۚ لَّوْ كَانُوا۟ يَفْقَهُونَ

Those who were left behind (in the Tabuk expedition) rejoiced in their inaction behind the back of the Messenger of Allah: they hated to strive and fight, with their goods and their persons, in the cause of Allah: they said, "Go not forth in the heat." Say, "The fire of Hell is fiercer in heat." If only they could understand!