Ayat al Quran

وَقُل رَّبِّ أَعُوذُ بِكَ مِنْ هَمَزَاتِ الشَّيَاطِينِ ﴿٩٧﴾

And say: "My Lord! I seek refuge with You from the whisperings of the Shayatin.''

Allah commanded him to seek refuge with Him from the Shayatin, because no trick could 

help you against them and you cannot protect yourself by being kind to them.

We have already stated, when discussing Isti`adhah (seeking refuge), that the Messenger 

of Allah used to say,

أَعُوذُ بِاللهِ السَّمِيعِ الْعَلِيمِ مِنَ الشَّيْطَانِ الرَّجِيمِ مِنْ هَمْزِهِ وَنَفْخِهِ وَنَفْثِه

I seek refuge with Allah, the All-Hearing, All-Seeing, from the accursed Shayatin, from his whisperings, 

evil suggestions and insinuations.

His saying:

وَأَعُوذُ بِكَ رَبِّ أَن يَحْضُرُونِ ﴿٩٨﴾ 

"And I seek refuge with You, My Lord! lest they should come near me.''

means, in any issue of my life.

So we are commanded to mention Allah at the beginning of any undertaking,
in order to ward off the Shayatin 

at the time of eating, intercourse, slaughtering animals for food, etc.

Abu Dawud recorded that the Messenger of Allah used to say:

اللَّهُمَّ

-       إِنِّي أَعُوذُ بِكَ مِنَ الْهَرَمِ،