سنن ابن ماجه

It was narrated from Ibn ‘Abbas that Dhu’aib Al-Khuza’i narrated that the Prophet (ﷺ) used to send the sacrificial animals with him, then he would say: “If any of them becomes unfit and you are afraid that it will die, then slaughter it, dip the sandal (tied around its neck) in its blood and place it on its side, but neither you nor any of your companions should eat anything from it.”