Such 'ayat are called "Muqatt'at" (Separated letters)...
Such 'ayat are called "Muqatt'at" (Separated letters), because they are recited one by one. Their meaning is known only to Allah, His Prophet and the 12 Imams. If anybody tries to interpret them according to his own notion he commits a great sin. So far as the above- mentioned "Muqaita'at" are concerned, there are two interpretations which have been narrated from our Imams:- Each of the 5 letters stands for a divine attribute.
"Kaf" - Stands for "kafi" (Charitable Giver or Self-Sufficient); "Ha" - stands for "Hadi" (Guide); "Ya" - stands for "Yad" (Hand, i.e.; Powerful); "'Ain" -stands for "Alim" (the All-Knowing); "Sad" - stands for "Sadiq" (The True One). According to another tradition Allah ordered Gabriel to teach Nabi Zakariya the sacred names of the Holy Prophet and his immediate Ahlul-Bait. When Gabriel mentioned the first 4 names (Muhammad, 'Ali, Fatimah, Hasan) Zakariya felt great joy.
But with the mention of the name of Husain, he was filled with grief and sorrow. When he asked Gabriel about this strange phenomenon, the latter acquainted him with the heart-rending tragedy of Karbala.
According to that Hadith, these 5 letter- symbols were used to convey to Zakariya the sad tidings of Karbala:- "Kaf" - stands for "Karbala"; "Ha" - is for "Halakat" (Anihilation of the Holy Family); "Ya" - stands for "Yazid"; "Ain" - stands for "'A tash" (Thirst) of Imam Husain and his companions; "Sad" - denotes their "Sabr" (patience). Q. 33. PEARL AND CORAL I am asking about Sura Rahman, verse 19. Does this verse refer to Imam Hasan and Imam Husain (a.s.)?
A: The 'ayat are as follows:- "He has let loose two seas that they flow together meeting each other; between them is a barrier so that they encroach not. Which then of the bounties of your Lord will you two belie? "Come forth out of the two (seas) pearl and coral.
Which then of the bounties of your Lord will you two belie?" (Ar-Rahman, 'Ayat19-23) According to the tradition of the Holy Prophet "The meeting of the two seas indicates the matrimonial union between Ali and Fatimah, and the "Barzakh", i.e., the barrier between the two seas is the Holy Prophet (so that they do not encroach upon the rights of each other), and the Pearl and Coral which come out of the two seas are Hasan and Husain." This tradition has been narrated by Ibn 'Abbas and Anas bin Malik and is quoted in the Sunni Tafsir, Ad-Durrul-Manthur.
Q34: MEANING OF AN AYA Surah Baqarah V.