One should not kill or cause to be killed an animal except in a sacrifice. Animals have become sacred for the kindness shown towards them by the creator, himself in the ordinance laid down by him.
वृथा पशुसमालम्भं नैव कुर्यान्न कारयेत्। अनुग्रहः पशूनां हि संस्कारो विधिनोदितः॥