Assalamalaykum, "Hayyak Allah" mean (Allah maintain your life) its is usually said, while greeting someone. It can be reply by saying "Allah Ye-hay-yeek!" الله يحييك Here are some useful Islamic phrases: Say "Assalamu Alaikum" (peace be on you) when meeting a Muslim. Say "Wa'alaikum Assalam" (peace be on you too) in reply. Say "Insha Allah" (if Allah wills) when hoping to do something. Say "Subhan Allah" (glory to Allah) when praising something. Say "Ma'sha Allah" (what Allah likes) in appreciation. Say "Fi Aman Allah" (in protection of Allah) when seeing someone off. Say "Jazak Allah Khairan" (may Allah give you the best reward) to thank someone. Say "Tawakkal-tu-Allah" (rely on Allah) to solve a problem. Say "Tawkkalna-Alai-Allah" (we have put our trust in Allah) when you wait for a problem to be solved. Say "La Ilaha Ill-Allah" (there is no god but Allah) when getting up in the morning. Say "Al-Hamdu Lillah" (praise be to Allah) when you sneeze. Say "Yarhamuk Allah" (may Allah bless you) when you hear someone sneeze. Say "Aameen" (accept our prayer) when joining a duaa. Say "Ya Allah" (O Allah) when in pain or distress. Say "Rahmah Allah" (Allah have Mercy on him) when you see someone in distress. Say "Astagh-firu-Allah" (O Allah forgive me) to be sorry for a bad action. Say "Na'uzhu-bi-Allah" (when we seek refuge in Allah) to show your dislike. Say "Inna Lillah" (we are for Allah) when you hear about the death of a Muslim. Say "Fe Sabeel Allah" (in/for Allah's cause/way) when you give charity/help people. Say "Atqaa Allah" (fear Allah) when you see someone doing a bad deed. Say "Allahu Yahdika" (may Allah guide you) to forbid sombody to do something indecent. Say "Hayyak Allah" (Allah maintain your life) when you greet someone. Say "Allah Aalam" (Allah knows best) when you say something you are not sure of. Say "Tabarak Allah" (blessed be Allah) when you hear a good news. Say "Hasbi Allah" (Allah will suffice me) when you are in a difficult situation. Say "Azhak Allah Sinnaka" (May Allah keep you cheerful) when you seek another Muslim with cheerful countenance. - Ref: Dictionary of Religious Terms by Dr. Abdullah Abu Eshy & Dr. Abdullah Latif. (Faculty of Arabic and Social Sciences; Islamic University of Imam Mohammad Ibn Saud)
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