Levítico 3:13 Midrash: Sifra

7) "and he shall slaughter it" "and he shall slaughter it" (Vayikra 3:8), "and he shall slaughter it" (Vayikra 3:13): Why three times? Because it is written (Devarim 12:21): "If the place be distant from you in which the L–rd your G d shall choose to place His name, (and you will not be able to come and bring peace-offerings every day, as you can now that the mishkan travels with you), then you shall slaughter of your herd and of your flock … and you shall eat in your gates with all the desire of your soul" — At a distance from the place (i.e., the Temple), you may slaughter (and eat), and not in proximity to the place — to exclude chullin (a non-consecrated animal) from being slaughtered in the azarah.

11) (Vayikra 3:2): "at the door of the tent of meeting," "before the tent of meeting" (Vayikra 3:8), "before the tent of meeting" (Vayikra 3:13) — to permit all the sides (of the azarah as slaughtering sites). It goes without saying that the north side (is permitted), viz.: If the other sides, which were not permitted for the slaughtering of higher-order offerings, were permitted for the slaughtering of lower-order offerings — the north side, which was permitted for the slaughtering of higher-order offerings, how much more so should it be permitted for the slaughtering of lower-order offerings! R. Eliezer says: "before the tent of meeting" — to permit the north side.