"Sacrificing cows is definitely in accordance with the requirements of shariah, rules the Fatawa-i-Rizvia. It cites an ayat from the Quran which does not have a word about the cows, .... It goes on to quote several ulema to the effect that slaughtering cows is an essential and long-standing practice of Islam. If Hindus object to the killing of cows on ‘communal grounds’—the grounds of the Hindus, note, are ‘communal’, the grounds of Muslims are spiritual obedience to Allah!—then it is not right for Muslims to refrain from killing cows. In fact, decrees the fatwa, on every occasion Muslims should keep up what has been prevalent in Islam for so long. If they stop it, they shall be sinners. The fatwa goes on reiterating this point, and returns to emphasize again that if the Hindu asks that cow-killing be stopped on account of his religious point of view, then it is not right for Muslims to stop killing the cows. And if the Hindu cites his false faith to have it stopped, then the Muslims must not stop it. And, warns the fatwa, the Islam of those who agree to do what they, the Hindus, are saying is counterfeit. For if you agree to their proposition you will be strengthening their false religion and doing so is not permissible in shariah. The fatwa proceeds to quote the fatwas which had been issued earlier by the ancestors of Abdul Bari and by Abdul Bari himself: that if someone restrains us from sacrificing a cow, then it becomes obligatory to sacrifice it, because we cannot give up our religious work under duress. Those who advocate the contrary to please the polytheists, the fatwa declares, are out to undermine Islam. They are great sinners, they are mufsid, they are amr-bil-haram, they are the enemies of Islam, they are the dacoits of Muslims, they are brothers of the Devil—Shaitan ke bhai, the workers for the Devil—Mis ke karinde, the enemies of truth, the heirs of the hypocrites. Quoting the Quran, the fatwa declares that they shall be consigned to Hell for ever. So much for persons—like Maulana Abdul Bari—who advocate that Muslims give up slaughtering cows. As for anyone who leaves the sacrifice of cows under their influence, the fatwa declares that he too is the enemy of Allah, the worker for Satan, the abandoner of that which is obligatory, and one fit for the fires of Hell. The continuation of the sacrifice of cows and the prohibition against participation in the meetings of Hindus, declares the Fatawa-i-Rizvia a little later, are both among the necessities of religion. He who declares the former haram and the latter halal— as Maulana Abdul Bari was doing, and as, in regard to meetings, Mufti Kifayatullah was doing—is calumnizing Allah and the Prophet. By the ordinances of the Holy Quran, declares the fatwa, his abode is Jahannum, Hell, and it is incumbent to apply the injunction of kufr upon him. And again: to stop sacrificing cows for the sake of Hindus is haram, declares Fatawa-i-Rizvia, citing as authority the Durr-ul-Mukhtar. And he who does what is haram, it pronounces, sets himself up for the torture of Jahannum, of Hell. He who is guilty of that which is kufr in Fiqh is out of Islam, his wives have become haram for him: he must embrace Islam again, he must go through the nikah again if he wants the status quo ante to be restored. And again: it is proper to continue sacrificing cows. To stop doing so out of consideration for Hindus is haram. Unity with Hindus is haram. And the ones who are advocating this unity (it was in the name of unity and, worse, as an expression of gratefulness that Abdul Bari, etc., were advocating that Muslims give up killing cows) ‘are by their own admission sacrificing the entire life of the Quran and Hadis on idolatry’."
January 1, 1970
https://en.wikiquote.org/wiki/Cattle_slaughter_in_India