Isti`adhah means, "I seek refuge with Allah from the cursed Satan so that he is prevented from affecting my religious or worldly affairs, or hindering me from adhering to what I was commanded, or luring me into what I was prohibited from.'' Indeed, only Allah is able to prevent the evil of Satan from touching the son of Adam. This is why Allah allowed us to be lenient and kind with the human devil, so that his soft nature might cause him to refrain from the evil he is indulging in. However, Allah required us to seek refuge with Him from the evil of Satan, because he neither accepts bribes nor does kindness affect him, for he is pure evil. Thus, only He Who created Satan is able to stop his evil. This meaning is reiterated in only three Ayat in the Qur'an. Allah said in Surat Al-A`raf,
[خُذِ الْعَفْوَ وَأْمُرْ بِالْعُرْفِ وَأَعْرِض عَنِ الْجَـهِلِينَ ](Show forgiveness, enjoin what is good, and turn away from the foolish (i.e. don't punish them).) (7:199)
This is about dealing with human beings. He then said in the same Surah,
[وَإِمَّا يَنَزَغَنَّكَ مِنَ الشَّيْطَـنِ نَزْغٌ فَاسْتَعِذْ بِاللَّهِ إِنَّهُ سَمِيعٌ عَلِيمٌ ](And if an evil whisper comes to you from Shaytan, then seek refuge with Allah. Verily, He is Hearing, Knowing (7: 200).)
Allah also said in Surat Al-Mu'minun,
[ادْفَعْ بِالَّتِى هِىَ أَحْسَنُ السَّيِّئَةَ نَحْنُ أَعْلَمُ بِمَا يَصِفُونَ - وَقُلْ رَّبِّ أَعُوذُ بِكَ مِنْ هَمَزَاتِ الشَّيـطِينِ - وَأَعُوذُ بِكَ رَبِّ أَن يَحْضُرُونِ ](Repel evil with that which is better. We are Best-Acquainted with the things they utter. And say: "My Lord! I seek refuge with You from the whisperings (suggestions) of the Shayatin (devils). And I seek refuge with You, My Lord! lest they should come near me.'' (23:96-98).)
Further, Allah said in Surat As-Sajdah,
[وَلاَ تَسْتَوِى الْحَسَنَةُ وَلاَ السَّيِّئَةُ ادْفَعْ بِالَّتِى هِىَ أَحْسَنُ فَإِذَا الَّذِى بَيْنَكَ وَبَيْنَهُ عَدَاوَةٌ كَأَنَّهُ وَلِىٌّ حَمِيمٌ - وَمَا يُلَقَّاهَا إِلاَّ الَّذِينَ صَبَرُواْ وَمَا يُلَقَّاهَآ إِلاَّ ذُو حَظِّ عَظِيمٍ - وَإِمَّا يَنزَغَنَّكَ مِنَ الشَّيْطَـنِ نَزْغٌ فَاسْتَعِذْ بِاللَّهِ إِنَّهُ هُوَ السَّمِيعُ الْعَلِيمُ ](The good deed and the evil deed cannot be equal. Repel (the evil) with one which is better, then verily he, between whom and you there was enmity, (will become) as though he was a close friend. But none is granted it (the above quality) except those who are patient ـ and none is granted it except the owner of the great portion (of happiness in the Hereafter, i.e. Paradise and of a high moral character) in this world. And if an evil whisper from Shaytan tries to turn you away (from doing good), then seek refuge in Allah. Verily, He is the Hearing, the Knowing) (41:34-36).