The word ya in Arabic is simply a vocative particle, that is, it functions like O or oh in English and is used when calling someone by name.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “I don’t find any reason to consider this to be a reprehensible practice. How could it be considered as such when by doing so, one is simply calling upon Allah by His most beautiful names? Didn’t Allah Himself tell us in the Qur’an that we may call upon Him by invoking any of His beautiful names: “Say: Call upon Allah or call upon Ar-Rahman (the All-Compassionate); by whatever name you call upon Him, to Him belong the most beautiful Names.” (Al-Isra’: 110)
How could we then consider calling upon the names of Allah to be a reprehensible innovation? If anyone does so, he is using the word too loosely. In fact, it should be a badge of honor for a believer to make his heart and tongue supple with such words of dhikr (remembrance of Allah), for it is the key to ultimate bliss, healing, and mercy. We read in a hadith that once a man asked the Prophet (peace and blessings be upon him), “I find the prescriptions of Islam too many to keep track of, so is there one thing you can tell me that I can cling to always?” The Prophet (peace and blessings be upon him) replied, “Let your tongue be supple with dhikr of Allah.”