The first ten verses of Al-Kahf
مَنْ حَفِظَ عَشْرَ آيَاتٍ مِنْ أَوَّلِ سُورَةِ الْكَهْفِ عُصِمَ مِنَ الدَّجَّالِ
Man hafidha 'ashra ayatin min awwali Surati-l-Kahf 'usima mina-d-Dajjal.
"Whoever memorises ten verses from the beginning of Surah Al-Kahf will be protected from the Dajjal."
Narrated by Abu ad-Darda'. Sahih Muslim 809
A short reflection
Ten verses is a small amount to carry for a great protection. Learn one a day and in under two weeks they are yours.