﴿ قَالَ ءَامَنتُمْ لَهُۥ قَبْلَ أَنْ ءَاذَنَ لَكُمْ ۖ إِنَّهُۥ لَكَبِيرُكُمُ ٱلَّذِى عَلَّمَكُمُ ٱلسِّحْرَ فَلَسَوْفَ تَعْلَمُونَ ۚ لَأُقَطِّعَنَّ أَيْدِيَكُمْ وَأَرْجُلَكُم مِّنْ خِلَٰفٍۢ وَلَأُصَلِّبَنَّكُمْ أَجْمَعِينَ ﴾

“Said [Pharaoh]: “Have you come to believe in him ere I have given you permission? Verily, he must be your master who has taught you magic! But in time you shall come to know [my revenge]: most certainly shall I cut off your hands and your feet in great numbers, because of [your] perverseness, and shall most certainly crucify you in great numbers, all together!””

بِعِزَّةِ فِرْ‌عَوْنَ (By the majesty of the Pharaoh - 26:44). This was an expression of pledge from the magicians, which was in vogue in the olden times. It is unfortunate that similar oaths have now become common among the Muslims as well, which are even more evil and vile, for instance, 'by the king,' 'by the head of yours,' 'by the beard of yours,' 'by the grave of your father' etc. It is not permitted to make an oath of this nature under the Islamic law (because swearing in the name of someone other than Allah is a sin). Rather, it will not be wrong to say that swearing a true oath in this way is as much sinful as swearing a false oath in the name of Allah. (Ruh)