"Then is it when it has occurred?" Al-Suddi said: It means: until when the punishment descends (fol. 140) "do you believe in it now, while you were before impatient for it?" Meaning: it is said to them when they believe upon the descent of the punishment: "Do you believe now, when belief will not avail you?"
﴿أَثم إِذا مَا وَقع﴾ قَالَ السُّدِّيُّ: يَعْنِي: حَتَّى إِذَا مَا نزل الْعَذَاب (ل ١٤٠) ﴿آمنتم بِهِ الآين وَقد كُنْتُم بِهِ تَسْتَعْجِلُون﴾ أَيْ: يُقَالُ لَهُمْ إِذَا آمَنُوا عِنْدَ نُزُولِ الْعَذَابِ الآنَ تَؤْمِنُونَ حِين لَا ينفعكم الْإِيمَان.