Heb. 'ammah; i.e., "mother of the arm," the fore-arm, is a word derived from the Latin cubitus, the lower arm. It is difficult to determine the exact length of this measure, from the uncertainty whether it included the entire length from the elbow to the tip of the longest finger, or only from the elbow to the root of the hand at the wrist. The probability is that the longer was the original cubit. The common computation as to the length of the cubit makes it 20.24 inches for the ordinary cubit, and 21.888 inches for the sacred one. This is the same as the Egyptian measurements.
A rod or staff the measure of a cubit is called in Judges 3:16 gomed , which literally means a "cut," something "cut off." The LXX. and Vulgate render it "span."
A linear measurement.
Consider the ravens: for they neither sow nor reap; which neither have storehouse nor barn; and God feedeth them: how much more are ye better than the fowls? And which of you with taking thought can add to his stature one CUBIT? ( Luke 12:24-25 )
ku'-bit ('ammah; pechus):
The standard for measures of length among the Hebrews. They derived it from the Babylonians, but a similar measure was used in Egypt with which they must have been familiar. The length of the cubit is variously estimated, since there seems to have been a double standard in both countries, and because we have no undisputed example of the cubit remaining to the present time. The original cubit was the length of the forearm, from the elbow to the end of the middle finger, as is implied from the derivation of the word in Hebrew and in Latin (cubitum). It seems to be referred to also in Deuteronomy 3:11: "after the cubit of a man." But this was too indefinite for a scientific standard, and the Babylonians early adopted a more accurate method of measurement which passed to the nations of the West. They had a double standard, the so-called royal cubit and the ordinary one. From the remains of buildings in Assyria and Babylonia, the former is made out to be about 20,6 inches, and a cubit of similar length was used in Egypt and must have been known to the Hebrews. This was probably the cubit mentioned by Ezekiel 40:5 and perhaps that of Solomon's temple, "cubits after the first measure" (2 Chronicles 3:3), i.e. the ancient cubit. The ordinary cubit of commerce was shorter, and has been variously estimated at between 16 and 18 or more inches, but the evidence of the Siloam inscription and of the tombs in Palestine seems to indicate 17,6 inches as the average length. See WEIGHTS AND MEASURES. This was the cubit of six palms, while the longer one was of seven (Ezekiel 40:5). The cubit mentioned in Judges 3:16 is from a different word in Hebrew (gomedh) and was probably shorter, for Ehud girded it on his thigh under his clothing.
The New Testament references are Matthew 6:27; Luke 12:25, "Which of you .... can add a cubit unto the measure of his life?"; John 21:18, "about two hundred cubits off"; Revelation 21:17, "the wall thereof, a hundred and forty and four cubits."
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