"And do not grieve for them" if they do not believe; meaning: the polytheists. "And do not be in distress over what they plot," meaning: do not let your chest become constricted by their plotting and their lying against you; for Allah is with you and "with those who fear Allah and those who are doers of good."
﴿وَلَا تحزن عَلَيْهِم﴾ إِنْ لَمْ يُؤْمِنُوا؛ يَعْنِي: الْمُشْرِكِينَ ﴿وَلا تَكُ فِي ضَيْقٍ مِمَّا يمكرون﴾ أَيْ: لَا يَضِيقُ صَدْرُكَ بِمَكْرِهِمْ وَكَذِبِهِمْ عَلَيْكَ؛ فَإِنَّ اللَّهَ مَعَكَ وَ ﴿مَعَ الَّذِينَ اتَّقَوْا وَالَّذِينَ هم محسنون﴾.