Hadith.4163 - Safwan ibn Yahya narrated from Abd al-Rahman ibn al-Hajjaj who said
I asked Abu Ibrahim (Imam Musa ibn Jafar Al-Kadhim (as)) about using a flint, a reed, or a piece of wood to slaughter an animal if one does not have a knife.
Imam (as) said: "If it cuts the veins, then there is no harm in it."