The Jews reckoned the day from sunset to sunset (Lev. 23:32). It
was originally divided into three parts (Ps. 55:17). "The heat
of the day" (1 Sam. 11:11; Neh. 7:3) was at our nine o'clock,
and "the cool of the day" just before sunset (Gen. 3:8). Before
the Captivity the Jews divided the night into three watches, (1)
from sunset to midnight (Lam. 2:19); (2) from midnight till the
cock-crowing (Judg. 7:19); and (3) from the cock-crowing till
sunrise (Ex. 14:24). In the New Testament the division of the
Greeks and Romans into four watches was adopted (Mark 13:35).
(See WATCHES T0003789.)

The division of the day by hours is first mentioned in Dan.
3:6, 15; 4:19; 5:5. This mode of reckoning was borrowed from the
Chaldeans. The reckoning of twelve hours was from sunrise to
sunset, and accordingly the hours were of variable length (John

The word "day" sometimes signifies an indefinite time (Gen.
2:4; Isa. 22:5; Heb. 3:8, etc.). In Job 3:1 it denotes a
birthday, and in Isa. 2:12, Acts 17:31, and 2 Tim. 1:18, the
great day of final judgment.