"Allahu Akbar" also referred to by the term Takbir, is an Islamic Arabic expression widely used by Muslims in various contexts. It is commonly translated as “God is [the] greatest” or "God is greater" in English.
Origin The phrase has been used by Muslims for over a millennium in various cultural and religious rituals, including as an expression of faith, distress call and declaration of victory. One of the earliest notable utterances of the Takbir on record is attributed to the Islamic prophet Muhammad at the Battle of Badr on March 13th, 624 A.D. - Source: KnowYourMeme
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