Praise be to Allah, Lord of the Worlds. May the good end be for the pious. May Allah's peace and blessings be upon His Slave and Messenger, our Prophet Muhammad (peace be upon him), who was sent as a mercy to the worlds and evidence against all people. May Allah's peace and blessings be upon his family and Companions who conveyed Allah's Book and the Messenger's Sunnah (whatever is reported from the Prophet) to those who came after them very honestly and thoroughly, while preserving the meanings and the words; may Allah be pleased with them, please them and make us among their followers in righteousness.

Scholars in the past and present have unanimously agreed on the sources on which rulings are based and strived to clarify what is Halal (lawful) and what is Haram (prohibited). These sources are: Allah's Book to which no falsehood can come in any way; the Sunnah of the Messenger of Allah (peace be upon him) who never spoke out of his own desire but only according to Wahy (Revelation); and then Ijma` (consensus of scholars).

Scholars disagreed over other sources, especially Qiyas (analogy). However, the Jumhur (dominant majority of scholars) consider it supporting evidence if all its conditions are met. The evidence of these sources are many.