Tosefta for Deuteronomy 21:2

It happened that two priests were running to go up the ramp. One pushed his fellow into the four cubit space. He took a knife and stabbed him in the chest. R. Zadok came and stood on the steps leading up the Ulam and said, "Hear me my Israelite brothers. Behold it says, (Deuteronomy 21) 'When one finds a dead body...and the elders and judges shall go out and measure...' Let us measure who should bring the calf, the sanctuary or the courtyards." Everyone groaned and cried. Afterwards the father of the young [priest] came and said, "My brothers, I am your atonement. My son's pulse is still beating and the knife has not yet been defiled." This shows that the impurity of the knife was more difficulty for Israel than bloodshed. And so it says, "Moreover, Manasseh put so many innocent persons to death that he filled Jerusalem [with blood] from end to end." From here they said, "Through the sin of bloodshed the Shekhinah departs and the Temple is defiled."