This is the thing
dabar  (daw-baw')
a word; by implication, a matter (as spoken of) or thing; adverbially, a cause
that ye shall do
`asah  (aw-saw')
to do or make, in the broadest sense and widest application
A third part
shliyshiy  (shel-ee-shee')
third; feminine a third (part); by extension, a third (day, year or time); specifically, a third-story cell) -- third (part, rank, time), three (years old).
of you entering
bow'  (bo)
to go or come (in a wide variety of applications)
on the sabbath
shabbath  (shab-bawth')
intermission, i.e (specifically) the Sabbath -- (+ every) sabbath.
of the priests
kohen  (ko-hane')
literally, one officiating, a priest; also (by courtesy) an acting priest (although a layman) -- chief ruler, own, priest, prince, principal officer.
and of the Levites
Leviyiy  (lay-vee-ee')
a Levite or descendant of Levi -- Leviite.
shall be porters
show`er  (sho-are')
a janitor -- doorkeeper, porter.
of the doors
caph  (saf)
a vestibule (as a limit); also a dish (for holding blood or wine) -- bason, bowl, cup, door (post), gate, post, threshold.