"If Allah should aid you, no one can overcome you," [referencing the verse]. Allah has informed His Messenger and the believers that they are granted victory, and likewise, if He abandons them, there will be no helper for them after Him.
﴿إِنْ يَنْصُرْكُمُ اللَّهُ فَلا غَالِبَ لكم﴾ الْآيَة، وَقد أعلم الله وَرَسُوله وَالْمُؤمنِينَ أَنهم منصورون، وَكَذَلِكَ إِن خذلهم لن ينصرهم من بعده نَاصِر.
