Hadith 8:3019
Abu Bakr narrated to us, he said: Ubayd Allah ibn Musa narrated to us, from Ayman ibn Nabil, from Abu Imran, he said: I asked Tawus about the saying of Allah, "Sawab" (standing in rows). He said: "It is to slaughter them while they are standing."
حدثنا أبو بكر قال نا عبيد الله بن موسى عن أيمن بن نابل أبي عمران قال سألت طاوسا عن قول الله @QB@ صواف @QE@ قال ينحر قياما