There is no prayer without Surah Fatiha. Some surahs are not required to be memorized, but emphasis is placed on learning them, such as Surah Kahf. Verse 6 of Surah Kahaf says, 'If they do not believe in this message, you may end up in sorrow by going back and forth behind them.'
There is a supplication in the tenth verse of this sura. This prayer was done by the cave-dwelling youths.
‘O our Lord, bestow favor upon us and arrange for us to conduct our affairs properly.' (Quran Sharif: Saral Banganubad, 'Sura Kahaf', Translation: Muhammad Habibur Rahman, First Edition)
The Prophet (PBUH) asked us to memorize the first ten verses of Surah Kahaf. There is a hadith, 'Whoever memorizes the first 10 verses of Surah Kahaf, he will be freed from Dajjal's trial.' (Muslim Sharif)
The first ten verses of Surah Kahaf cover some of the fundamentals of Islam. 'And to warn those who say that Allah has taken children, they have no knowledge of this, nor did their forefathers. Strange words come out of their mouths, they only speak lies.' (Surah Kahf, 4-5)
