Thus ignorant is that person who will not do animal sacrifice considering it an act lacking mercy. Similarly the statement of some opponents, after seeing animal sacrifice, that Muslims are merciless, this is serious mistake on their part because mercy is a state of spell. Everybody knows his state and can not find the state of other person at all. Even in spite of the fact that Muslims indulge in animal sacrifice the argument for them being people of mercy is that they can not see the pain of any animal. In fact, by God, Muslims have mercy even during the very act of sacrifice. And their hearts are softened at the sight f sacrifice. Thus Hazrat Maulana Mehmood Hasan Deobandi (RA) once sacrificed an animal for which the butcher was ready to pay eighty rupees but Maulana did not sell and sacrificed it. But it is reported that Maulana was doing the sacrifice and was crying too. Now see how great this struggle is? The heart is completely watered down but still completing the sacrifice. That is the sacrifice of baser self-to act against the desires of the baser self.
Source : Ashrafia (Khutbat-e-Hakim-ul-Ummat, Sunnah of Ibraheem, Lecture Delivered by Hazrat Maulana Ashraf Ali Thanwi (RA) at Kairana, Muzaffar Nagar, on 24 Zi-Qadah, 1335AH and published in the Periodical Imdad, Lahore, Zi-Qadah 1421AH, February 2001AC, p.64-65)