Commentaire sur Les Nombres 17:13

ויעמד בין המתים וגו׳ AND HE STOOD BETWEEN THE DEAD [AND THE LIVING] — He (Aaron) seized the Angel of Death and stopped him despite himself. The angel said to him, “Let me be, so that I may carry out my commission!” He (Aaron) answered him, “Moses has bidden me prevent you”. The angel replied, “I am the messenger of the Omnipresent whilst you are but the messenger of Moses!” Aaron retorted, “Moses does not say anything out of his own mind, but only at the command of the Almighty. If you do not believe me, behold, the Holy One, blessed be He, and Moses are at the entrance of the appointed tent; come with me and ask them!” This is the meaning of what is stated (v. 15): And Aaron returned unto Moses (i.e. returned together with the Angel of Death) (cf. Midrash Tanchuma, Tetzaveh 15 at end of תצוה). Another explanation is: Wherefore was the plague stayed by means of the incense? Because the Israelites were traducing and speaking ill of the incense, saying, “It is a deadly poison: through it Nadab and Abihu died; through it the two hundred and fifty men were burnt!” therefore the Holy One, blessed be He, said, You will see that it is also a means for restraining the plague, and it is only sin that brings death” (Mekhilta d'Rabbi Yishmael 17:5:3 on Exodus 17:5).

ויעמוד בין המתים ובין החיים, after he had already reached that spot he waited in order to help cure the ones who had taken sick but had not died yet. Instead of distancing himself from the congregation of sinners (verse 21) Aaron did the opposite in order to save whom he could save.

ויעמד בין המתים ובין החיים. He stood between the dead and between the living. This expression can best be understood with the help of Tanchuma on Tetzaveh paragraph 15. The Midrash explains there that Aaron took hold of the angel of death physically and prevented him from killing. At the same time he counted the number of dead to make sure that the angel of death would not add to their number. The correct translation of our verse then is: "he stood, i.e. arrested or limited the number of dead that had died from amongst the living." This explains why the Torah added that at that moment the number of dead from the plague was (already) 14,700. No additional people died once Aaron offered the incense.