(Iblis) said;"By Your might, then I will surely mislead them all, except Your true servants amongst them."
This is like the Ayat;
أَرَءَيْتَكَ هَـذَا الَّذِى كَرَّمْتَ عَلَىَّ لَيِنْ أَخَّرْتَنِ إِلَى يَوْمِ الْقِيَـمَةِ لَاحْتَنِكَنَّ ذُرِّيَّتَهُ إَلاَّ قَلِيلً
(Iblis) said;"See this one whom You have honored above me, if You give me respite until the Day of Resurrection, I will surely seize and mislead his offspring all but a few!" (17;62)
These few are the ones who are excepted in another Ayah, which is;
إِنَّ عِبَادِى لَيْسَ لَكَ عَلَيْهِمْ سُلْطَـنٌ وَكَفَى بِرَبِّكَ وَكِيلً
Verily, My servants -- you have no authority over them. And All-Sufficient is your Lord as a Guardian. (17;65)
قَالَ فَالْحَقُّ وَالْحَقَّ أَقُولُ