In Islam, for an animal to be halal, it must be slaughtered according to Islamic law, which includes reciting “Bismillah” (in the name of Allah) before the cut. The Quran explicitly instructs Muslims to consume meat from animals over which Allah’s name has been mentioned and prohibits eating from animals slaughtered without it (Al-An’am 6:118, 6:121). The Hanafi, Maliki, and Hanbali schools of thought view saying “Bismillah” as obligatory, considering meat from animals slaughtered without it as impure. However, forgetfulness is an exception according to the Hanafi and Maliki schools.
The Shafi’i school regards saying “Bismillah” as a highly emphasized Sunnah, not obligatory, but still recommends avoiding meat from animals where the recitation was deliberately omitted.