Praise be to Allah the Lord of the Worlds.
According to the Prophetic Sunnah, "Al-Ahad"(The Unique) is one of the names of Allah. It was narrated from Abu Hurairah that : the Messenger of Allah (saas) said: "Allah has ninety-nine names, one hundred less one, for He is One and loves the odd (numbered). Whoever learns them will enter Paradise. They are: Allah, Al-Wahid (the One), As-Samad (the Self-Sufficient Master who all creatures need, He neither eats nor drinks), Al-Awwal (the First), Al-Akhir (the Last), Az-Zahir (the Most High), Al-Batin (the Most Near), Al-Khaliq (the Creator), Al-Bari (the Inventor of all things), Al-Musawwir (the Bestower of forms), Al-Malik (the King), Al-Haqq (the Truth), As-Salam (the One free from all defects), Al-Mu'min (the Giver of security), Al-Muhaymin (the Watcher over His creatures), Al-'Aziz (the All-Mighty), Al-Jabbar (the Compeller), Al-Mutakabbir (the Supreme), Ar-Rahman (the Most Gracious), Ar-Rahim (the Most Merciful), Al-Latif (the Most Subtle and Courteous), Al-Khabir (the Aware), As-Sami' (the Hearing), Al-Basir (the Seeing), Al-'Alim (the All-Knowing), Al-'Azim (the Most Great), Al-Barr (the Source of goodness), Al-Muta'al (the Most Exalted), Al-Jalil (the Sublime One), Al-Jamil (the Beautiful), Al-Hayy (the Ever-Living), Al-Qayyum (the One Who sustains and protects all that exists), Al-Qadir (the Able), Al-Qahir (the Irrestible), Al-'Ali (the Exalted), Al-Hakim (the Most Wise), Al-Qarib (the Ever-Near), Al-Mujib (the Responsive), Al-Ghani (the Self-Sufficient), Al-Wahhab (the Bestower), Al-Wadud (the Loving), Ash-Shakur (the Appreciative), Al-Majid (the Most Gentle), Al-Wajid (the Patron), Al-Wali (the Governor), Al-Rashid (the Guide), Al-'Afuw (the Pardoner), Al-Ghafur (the Forgiver), Al-Halim (the Forbearing One), Al-Karim (the Most Generous), At-Tawwab (the Acceptor of Repentance), Ar-Rabb (the Lord and Cherisher), Al-Majid (the Most Glorious), Al-Wali (the Helper), Ash-Shahid (the Witness), Al-Mubin (the Manifest), Al-Burhan (the Proof), Ar-Ra'uf (the Compassionate), Ar-Rahim (the Most Merciful), Al-Mubdi' (the Originator), Al-Mu'id (the Restorer), Al-Ba'ith (the Resurrector), Al-Warith (the Supreme Inheritor), Al-Qawi (the All-Strong), Ash-Shadid (the Severe), Ad-Darr (the One Who harms), An-Nafi' (the One Who benefits), Al-Baqi' (the Everlasting), Al-Waqi (the Protector), Al-Khafid (the Humble), Ar-Rafi' (the Exalter), Al-Qabid (the Retainer), Al-Basit (the Expander), Al-Mu'izz (the Honorer), Al-Mudhill (the Humiliator), Al-Muqsit (the Equitable), Ar-Razzaq (the Providor), Dhul-Quwwah (the Powerful), Al-Matin (the Most Strong), Al-Qa'im (the Firm), Ad-Da'im (the Eternal), Al-Hafiz (the Guardian), Al-Wakil (the Trustee), Al-Fatir (the Originator of creation), As-Sami' (the Hearer), Al-Mu'ti (the Giver), Al-Muhyi (the Giver of life), Al-Mumit (the Giver of death), Al-Mani' (the Withholder), Al-Jami' (the Gatherer), Al-Hadi (the Guide), Al-Kafi (the Sufficient), Al-Abad (the Eternal), Al-'Alim (the Knower), As-Sadiq (the Truthful), An-Nur (the Light), Al-Munir (the Giver of light), At-Tamm (the Perfect), Al-Qadim (the Earlier), Al-Witr (the One), Al-Ahad (the Lone), As-Samad [(the Self-sufficient Master, Who all creatures need, (He neither eats no drinks)]. He begets not, nor was He begotten. And there is none co-equal or comparable unto him."(One of the narrators) Zuhair said: We heard from more than one of the scholars that the first of these (names) should begin after saying: La ilaha illallahu wahdahu la sharika lahu, lahul-mulku wa lahul-hamdu, bi yadihil-khair wa Huwa 'ala kulli shay-in Qadir, la ilaha illallahu lahul-asma'ul-husna [None has the right to be worshipped but Allah, with no partner or associate. His is the dominion and all praise is His. In His Hand is (all) goodness, and He is Able to do all things, none has the right to be worshipped but Allah, and His are the (Most) Beautiful Names].'{Ibn Majah & Al-Baihaqhi}.
The names and attributes of Allah, in terms of permissibility of calling any human with them, fall into two categories: 1. Names and attributes that only belong to Him, may He be glorified and exalted, and cannot be given to anyone but Him, such as the names Allah, Al-Rabb (The Lord or Cherisher), Al-Awwal (the First), Al-Akhir (the Last), and the like. It is not permissible to call any human being by these, according to scholarly consensus. 2. Names and attributes which do not apply only to Him, and which may be applied to human beings, so it is permissible to call people by them. The evidence on this is that Allah the Almighty has described His Prophet (PBUH) as: "…….. full of pity, merciful."{At-Tawbah, 128}.
He the Exalted has also described man as Samee’ (hearing), Baseer (seeing) where he the Almighty said, " Lo! We create man from a drop of thickened fluid to test him; so We make him hearing, knowing."{Al-Insaan, 2}. All of these are attributes of Allah, but He described man with them to suit the latter`s weakness, but described Himself with them to suit His absolute perfection.
As for the ruling on naming a child "Al-Ahad", according to the Shafie school of thought, there is no saying for the Shafie scholars about that. By analogy to the aforementioned, it isn`t permissible to name a child "Al-Ahad" as this name belongs only to Allah the Almighty. Al-Shirbini (May Allah be pleased with him) said, "It is not permissible to use the name "Malik Al-Ammlaak" save for Allah the Almighty"{Moghni Al-Mohtaaj, 6/141}. And Allah the Almighty knows best.
