The word "day",
when used without any limiting words, may refer to a long or prolonged period:
as,
The "day of Grace",
The "day of Visitation"
The "day of Salvation",
The "day of Judgment"
The "day of the Lord" "man's day"
But when the word "day" is used with a numeral
(cardinal or ordinal), as one, two, three, etc., or first, second, third, etc.,
"evening and morning" (Genesis 1), or the "seventh day"
(Exodus 20:9,11,
etc.), it is defined, limited, and restricted to an ordinary day of
twenty-four hours.
Exodus 20:9 Six days shalt thou labour, and do all thy work:
Exodus 20:11 For in six days the LORD made heaven and earth, the sea, and
all that in them is, and rested the seventh day: wherefore the LORD blessed the
sabbath day, and hallowed it.
The word "day" is never used for a year. Sometimes a corresponding
number of days is used for a corresponding number of years, but in that case it
is always expressly stated to be so used; as in Numbers 14:33,34.
Numbers14:33 And your children shall wander in the wilderness forty years,
and bear your whoredoms, until your carcases be wasted in the wilderness.
Numbers 14:34 After the number of the days in which ye searched the land,
even forty days, each day for a year, shall ye bear your iniquities, even forty
years, and ye shall know my breach of promise.
But, even in these cases, the word "day" means a day, and the word
"year" means a year. It is not said that a day means a year; but
the number of forty years is said to be "after the number of days in
which ye searched the land, even forty days.
It is the same in Ezekiel 4:5,
Ezekiel 4:5 For I have laid upon thee the years of their iniquity, according
to the number of the days, three hundred and ninety days: so shalt thou bear the
iniquity of the house of Israel.
Where
the years of Israel's iniquity were laid on Ezekiel "according to the
number of days". In this case also, the word "days" means
days, and the word "years" means years.
There is no Scriptural warrant for arbitrarily assuming this to be a general
principle in the absence of any statement of that effect.