The other instances of names for the months are Nisan, Sivan, Elul, Chisleu, Tebeth, Sebat, and Adar, derived from month names in use in Babylonia, and employed only in the books of Esther, Ezra, Nehemiah, and Zechariah, all avowedly post-exilic writers. The month word used in connection with them is chodesh—since the Babylonian months were also lunar—except in the single case where Ezra used a month name, terming it yerach. The other post-exilic writers or editors of the books of Holy Scripture would seem to have been at some pains to omit all Babylonian month names. These Babylonian month names continue to be used in the Jewish calendar of to-day.
In four places in Scripture mention is made of a month of days, the word for month being in two cases chodesh, and in two, yerach. Jacob, when he came to Padan-aram, abode with Laban for "the space of a month," before his crafty uncle broached the subject of his wages. This may either merely mean full thirty days, or the term chodesh may possibly have a special appropriateness, as Laban may have dated Jacob's service so as to commence from the second new moon after his arrival. Again, when the people lusted for flesh in the wilderness, saying, "Who shall give us flesh to eat?" the Lord promised to send them flesh—
"And ye shall eat. Ye shall not eat one day, nor two days, nor five days, neither ten days, nor twenty days, but even a whole month. . . . And there went forth a wind from the Lord, and brought quails from the sea."
"He rained flesh also upon them as dust,
And feathered fowls like as the sand of the sea."
The "whole month" in this case was evidently a full period of thirty days, irrespective of the particular phase of the moon when it began and ended.
Amongst the Babylonians the sign for the word month was xxx, expressing the usual number of days that it contained, and without doubt amongst the Hebrews that was the number of days originally assigned to the month, except when the interval between two actually observed new moons was found to be twenty-nine. In later times it was learned that the length for the lunation lay between twenty-nine and thirty days, and that these lengths for the month must be alternate as a general rule. But in early times, if a long spell of bad weather prevented direct observation of the new moon, we cannot suppose that anything less than thirty days would be assigned to each month.
Such a long spell of bad observing weather did certainly occur on one occasion in the very early days of astronomy, and we accordingly find that such was the number of days allotted to several consecutive months, though the historian was evidently in the habit of observing the new moon, for chodesh is the word used to express these months of thirty days.
We are told that—
"In the six hundreth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened."
And later that—