Midrasch zu Jechezkiel 4:14

(Fol. 37b) It is written (Ez. 4, 14) Then said I, 'Oh, Lord God! Behold, my soul hath not been polluted; for from my youth up even till now have I not eaten of that which dieth of itself, or is torn of beasts; neither came there abhorred flesh into my mouth.' i.e., Behold, my soul has not been polluted. I allowed no impure thoughts to arise in me in the day-time, which should cause me uncleanliness during the nighttime. For from my youth up I have not eaten of that which dieth of itself; this means that meat of an animal about which one says cut, cut, i.e., meat of an animal hurriedly cut, because it threatens to die. Neither came there abhorred flesh into my mouth; this means that I have not eaten of an animal upon which is required the decision of a scholar [whether it is permitted to be eaten or not]. R. Nathan said: "It means that I have not eaten of an animal of which the priestly gifts were not set aside."