Midrash su Salmi 71:6

GEMARA: In what principal do the above Tannaim differ? One holds that the real life of man comes from his nostrils and the other holds that life comes through the navel. Shall we assume that the above Tannaim differ in the same principal as that of the following Mishnah? From what part is the embryo created? From the head, and so also says the passage (Ps. 71, 6) Thou art He that took me out of my mother's womb, and again it is said (Jer. 7, 29) Cut off thy flowing hair, and cast it away. Abba Saul says: "The creation [of an embryo] begins from the navel and it develops on both sides." [Hence we see that the above Tanaim differ in the same principle as that of our Mishnah]. Both Tanaim of our Mishnah can be reconciled even with the opinion of R. Saul, for R. Saul merely stated concerning the creation of the body, but he does not refer to the soul, to which all may agree, that it comes through the nostrils, as it is said (Gen. 7, 22) All in whose nostrils was the breath of life. R. Eliezer b. Jacob says: "From the place where the slain was killed — from his throat." What is the reason of R. Eliezer b. Jacob? He derives it from the following passage, (Ez. 21, 34) To lay thee upon the necks of the wicked that are to be slain.