Ma'arif al-Qur'an
Mufti Muhammad Shafiقَالَ آمَنتُمْ لَهُ قَبْلَ أَنْ آذَنَ لَكُمْ (He [ the Pharaoh ] said, "You have believed in him before I permit you" - 20:71). The Pharaoh, thus disgraced before a vast multitude, was furious and he stormed at the magicians how they dared accept the religion brought by Sayyidna Musa (علیہ السلام) without his prior permission. He suspected that they all were Sayyidna Musa's (علیہ السلام) pupils who taught them the magic and had accepted defeat in connivance with him.فَلَأُقَطِّعَنَّ أَيْدِيَكُمْ وَأَرْجُلَكُم مِّنْ خِلَافٍ (I will certainly cut apart your hands and your legs from opposite sides - 20:71). The Pharaoh thus threatened his magicians with dire punishment. He said he would cut off their hands and feet from opposite sides i.e. first the right hand, then the left foot. This apparently was the mode of inflicting punishment under the laws of the Pharaoh.
وَلَأُصَلِّبَنَّكُمْ فِي جُذُوعِ النَّخْلِ (And will crucify you on the trunks of palm-trees - 20:71) He also said that after cutting off their hands and feet he would crucify them on the trunks of palm-trees where they would remain suspended until they died of starvation.