فَرِحَ الْمُخَلَّفُونَ بِمَقْعَدِهِمْ خِلَافَ رَسُولِ اللَّهِ وَكَرِهُوا أَن يُجَاهِدُوا بِأَمْوَالِهِمْ وَأَنفُسِهِمْ فِي سَبِيلِ اللَّهِ وَقَالُوا لَا تَنفِرُوا فِي الْحَرِّ ۗ قُلْ نَارُ جَهَنَّمَ أَشَدُّ حَرًّا ۚ لَّوْ كَانُوا يَفْقَهُونَ
“Those [hypocrites] who remained behind rejoiced for doing so in defiance of the Messenger of Allah, and hated [the prospect of] striving with their wealth and their lives in the cause of Allah. They said [to one another], 'Do not march forth in the heat.' Say, [O Prophet,] 'The Fire of Hell is far hotter!' If only they could comprehend!”
On the hypocrites rejoicing at staying behind from Tabuk.
This ayah is part of Surat al-Tawba's Tabuk-era passage addressing the hypocrites and excuse-makers who stayed behind or mocked the campaign, described at this event.