Isti’adhah is to say: A’ooudhu billahi min-ash-shaitaan-ir-rajeem. It means, “I seek refuge with Allah from the cursed Satan.”

Allah’s refuge is sought from Shaitan to prevent him from affecting our religious or worldly affairs or hindering us from adhering to what we are commanded, or luring us into what we are prohibited from. Only Allah is able to prevent the evil of Satan from touching the son of Adam.

Allah allowed us to be lenient and kind with human devils (sinners and wrongdoers among human beings) because soft nature may refrain such sinners from the evil they are indulging in. However, Allah required us to seek refuge from the evil of Satan because Satan 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 verses in the Qur’an. Allah said in Surat Al-A`raf:

“Show forgiveness, enjoin what is good, and turn away from the foolish (i.e. don’t punish them).” (Qur’an, 7:199)

This verse is about dealing with human beings. Allah then said in the next verse:

“And if an evil whisper comes to you from Shaytan, then seek refuge with Allah. Verily, He is All-Hearer, All-Knower.” (Qur’an, 7: 200)

Allah also said:
“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 – 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 All-Hearer, the All-Knower.” (Qur’an, 41:34-36)

– Ibn Kathir’s Tafsir of Surah Fatihah