The phrase means "O [name]". Literally, the word Yā means O (as in a call to someone). It is a common prefix used by Arabs to call each other. Someone named Zaid will be addressed in Arabic as Yā Zaid.
The word Yā alone is of no religious significance. It is used as well with derogatory and abusive words in Arabic, for example in Yā kadhdhāb (یا کذاب) "O Liar".
Request for strength
Ya Ali is mostly used as a request for strength in the phrase Ya Ali Madad (یا علی مدد, Ali, help!) because he is the Imamah Imam in Shia Islam.
Other phrases are mostly used as slogans which are meant to increase one's level of morale in certain situations and also increase the religious passion. These phrases are mostly used in religious gatherings.
Remembrance of Muharram
During the Remembrance of Muharram, spontaneous slogans of Ya Hussain, Ya ‘Ali and Ya Rasulul-Lah "Messenger of God!" are very common. On such occasions, the slogans are mostly demonstrations of strong support.
Muslims visiting the grave of Muhammad recite As-salatu as-salamu alayka, Ya Rasulul-Lah "Greetings and peace be upon you, O Messenger of God". Shia Muslims use similar kinds of greetings while visiting graves and shrines of other holy personalities.
In Saudi Arabia, Yā Muhammad is used to address a stranger in order to begin a conversation. It is considered one of the polite and respectful ways to address a stranger, as Muhammad is considered as the most respectful name anyone can be called, hence its popularity among Muslims worldwide.
In popular culture
A popular Hindi/Urdu song in India is Yā ‘Alī (Urdu: یا علی, Hindi: या अली), sung by Assamese singer Zubeen Garg. The song, basically a fast techno-fusion romantic track, is a plea to Ali for a lover. The song’s words are written by Sayeed Qadri. The song is from the soundtrack of the Bollywood film, Gangster.
Arguments For and Against
Those who support using Yā derive their support from the articles of faith, There is no god but God and Muhammad is the messenger of God". As this cannot be changed, they claim that Muhammad is still alive because Muhammad is the messenger of Allah, not was. There are also some arguments from the Qur'an, such as the Qur'anic verse that states "Do not consider those who die on the path for Islam to be dead." (2:154) In addition, a plaque on the Prophet's grave to this day reads "As-salāmu ‘alayka, Yā Rasūlu l-Lāh" "Peace be upon you, O Prophet of God", highlighting that the Salafis, who run the mosque, themselves should agree with the practice.
Those who practice this are mainly Shi'as and Sufis.
This practice is regarded as wrong by some Muslims, arguing that no one needs an intermediary to speak to God. There are some sects and groups who consider this to be an innovation and idolatry, because only God alone can help and no one else. They derive their support from the Qur'an where it states, "Do not recall any god beside me...Ask me directly if you are in need."
The Islamic revival movements in the late colonial period developed puritan thoughts in islamic theology. Groups which condemn the phrase ya to anyone than God are today known as salafis, a school of thought within the sunni sect of islam. Others, like the Deobandis, allow limited use of "Ya Muhammad", such as when sending peace and blessings upon the Prophet of Islam.