From Historic point of view, Was it being practiced by pre-Islamic Arab Tribes?? Did other prophets of God ( Messiah and Moses) before Prophet Muhammad (PBUH) also practiced it and made obligatory for their followers(jews/Christians) or not?? Is importance of this obligation also mentioned in all other divine books(Bible, Torah, Zaroor, Gita etc) What would be guidelines regarding Sacrifice of animals for a believer who is vegetarian ethically or activist of PETA(Peoples for Ethical Treatment of Animals).