﴿ وَتِلْكَ حُجَّتُنَآ ءَاتَيْنَٰهَآ إِبْرَٰهِيمَ عَلَىٰ قَوْمِهِۦ ۚ نَرْفَعُ دَرَجَٰتٍۢ مَّن نَّشَآءُ ۗ إِنَّ رَبَّكَ حَكِيمٌ عَلِيمٌۭ ﴾

“And this was Our argument which We vouchsafed unto Abraham against his people: [for] We do raise by degrees whom We will. Verily, thy Sustainer is wise, all-knowing.”

That argument of Ours, that is, the argument for affirming [God's] Oneness with which Abraham used against his people.