On the eleventh day - The Hebrew form of expression, here and in the 78th verse, has something curious in it. ביום עשתי עשר יום beyom ashtey asar yom, In the day, the first and tenth day; ביום שנים עשר יום beyom sheneym asar yom, In the day, two and tenth day. But this is the idiom of the language, and to an original Hebrew our almost anomalous words eleventh and twelfth, by which we translate the original, would appear as strange as his, literally translated, would appear to us. In reckoning after twelve, it is easy to find out the composition of the words thirteen, as three and ten, fourteen, four and ten, and so on; but eleven and twelve bear scarcely any analogy to ten and one, and ten and two, which nevertheless they intend. But this is a subject of philology rather than of Biblical criticism.

Numbers 1:15 Of Naphtali; Ahira the son of Enan.

Numbers 2:29 Then the tribe of Naphtali: and the captain of the children of Naphtali shall be Ahira the son of Enan.

Numbers
Like the last part of Exodus, and the whole of Leviticus, the first part of Numbers, i.-x. 28--so called,[1] rather inappropriately, from the census in i., iii., (iv.), xxvi.--is unmistakably priestly in its interests and language. Beginning with a census of the men of war (i.) and the order of the camp (ii.), it devotes specific attention to the Levites, their numbers and duties (iii., iv.). Then follow laws for the exclusion of the unclean, v. 1-4, for determining the manner and amount of restitution …
John Edgar McFadyen—Introduction to the Old Testament