Reference : Hisn al-Muslim 146

كان رسول الله صلى الله عليه وسلم يعوذ الحسن والحسين
" أعيذكما بكلمات الله التامة ،
من كل شيطان وهامة ، 
ومن كل عينِ لامة "
The Prophet (ﷺ) used to seek Allah's protection for Al-Hasan and Al-Husain by saying:

U`īthukumā bikalimāti ‘llāhit-tāmmati 
min kulli shayṭānin wa hāmmah, 
wa min kulli `aynin lāmmah


I seek protection for you in the Perfect Words of Allah 
from every devil and every beast, 
and from every envious blameworthy eye.

Reference:
Al-Bukhari4/119.

Chapter: Placing childen under Allah’s protection