"Then the one between whom and you there is enmity, [will become] as though he were a devoted friend." That is: a close relative.
﴿فَإِذَا الَّذِي بَيْنَكَ وَبَيْنَهُ عَدَاوَةٌ كَأَنَّهُ ولي حميم﴾ أَي: قريب قرَابَته