﴿ وَلَئِنْ أَرْسَلْنَا رِيحًۭا فَرَأَوْهُ مُصْفَرًّۭا لَّظَلُّوا۟ مِنۢ بَعْدِهِۦ يَكْفُرُونَ ﴾

“But thus it is: if We send a wind [that scorches their land], and they see it turn yellow, they begin, after that [erstwhile joy], to deny the truth [of Our almightiness and grace]!”

(And if We sent a wind) cold or hot wind on their vegetation (and they beheld it) i.e. the vegetation (yellow) when it was green before that; (they verily would still continue in their disbelief) even after seeing it turn yellow, they would still disbelieve in Allah and show no gratitude towards Him.