﴿ لَقَدْ كَانَ لَكُمْ فِيهِمْ أُسْوَةٌ حَسَنَةٌۭ لِّمَن كَانَ يَرْجُوا۟ ٱللَّهَ وَٱلْيَوْمَ ٱلْءَاخِرَ ۚ وَمَن يَتَوَلَّ فَإِنَّ ٱللَّهَ هُوَ ٱلْغَنِىُّ ٱلْحَمِيدُ ﴾

“In them, indeed, you have a good example for everyone who looks forward [with hope and awe] to God and the Last Day. And if any turns away, [let him know that] God is truly self-sufficient, the One to whom all praise is due."”

As far as justice and fair play are concerned, they will be given to everybody–whether friend or foe. But having friendships with those who are at war with one is not proper.