HOUR. The word “hour” as a division of the day is not found in the OT, for the Israelites had no system of equal hours for dividing the day. In the earlier periods of OT history the only divisions of the natural day were morning, noonday, and evening (Gen 1:5; 43:16). The night appears under the threefold division of first, middle, and morning watches (Exod 14:24; Judg 7:19; Lam 2:19).

In the OT the word appears only in the KJV (Dan 3:6, 15 RSV “immediately”; 4:33 RSV “immediately”; 4:19 RSV “for a long time”; 5:5 “immediately”), but it does not have the meaning it has today.

Apparently the Babylonians were among the first to adopt the division of twelve equal parts for the day. Herodotus testifies (II, 109) that the Greeks derived this custom from the Babylonians. The sun dial of Ahaz (2 Kings 20:11; Isa 38:8) was undoubtedly introduced from Babylonia.

International Standard Bible Encyclopedia (1915)

Hour as a division of the day does not occur in the Old Testament; the term she`a’ (sha`atha’) found in Dnl, is Aramaic, and as used there denotes a short period or point of time of no definite length (Da 3:6,15; 4:33 (Hebrew 30); 5:5). The Greek hora is commonly used in the New Testament in the same way, as "that same hour," "from that hour," etc., but it also occurs as a division of the day, as, "the third hour," "the ninth hour," etc. The Hebrews would seem to have become acquainted with this division of time through the Babylonians, but whether before the captivity we are not certain. The mention of the sun dial of Ahaz would seem to indicate some such reckoning of time during the monarchy.

See Time.