Q 91: What is the proof of the differences among their Shara’i` (pl. Shari'ah) laws pertaining to what is lawful [Halal] and what is unlawful [Haram]?
A--- Almighty Allah says in His Glorious Qur'an, {To each among you, We have prescribed "Shir`ah wa Minhaj” a law and a clear way. If Allah had willed, He would have made you one nation, but that (He) may test you in what He has given you; so compete in good deeds}. (Al-Ma'idah,48)
Ibn 'Abbas (May Allah be pleased with them) said: "Shir`ah wa Minhaj means a law and a clear way." The same viewpoint was held by Mujahid, `Ikrimah, Al-Hasan Al-Basri, Qatadah, Ad-Dahhak, As-Sadyi, and Abu Ishaq As-Subai`i.
In Sahih AI-Bukhari, Prophet Muhammad (Peace be upon him) says: "The Prophets are paternal brothers, their mothers are different, but their religion is one.” (20) He means the Monotheism or Tawhid (The Oneness of Allah) with which Allah the Almighty sent all Messengers and Prophets, and that which He, Glory be His, revealed in all His Books. But, as for the laws, they are different pertaining to the ordainments and prohibitions, the lawful and the unlawful, {That He might try you, which of you is the best in deeds}. (Hud, 7)
Reference: 200 FAQ On Muslims Belief - Shiekh Hafiz Ibn Ahmed Al Hakami
(20) Transmitted by AI-Bukhari (3442) and Muslim (2395) after Abu Hurairah with the following wording: "Both in this world and in the Hereafter, I am the nearest of all the people to Jesus, the son of Mary. The Prophets are paternal brothers; their mothers are different, but their religion is one.