Jewish Encyclopedia, p. 591- 597
"In order to fix the beginning and ending of the Sabbath-day and festivals and to determine the precise hour for certain religious observances it becomes necessary to know the exact times of the rising and setting of the sun. According to the strict interpretation of the Mosaic law, every day begins with sunrise and ends with sunset... "
Vine’s Complete Expository Dictionary of Old and New Testament Words
“In the Hebrew mind the “DAY” began at the rising of the sun.”
Ancient Israel, p. 181 - 182
“In Israel, the day was for a long time reckoned from morning to morning… and it was in fact in the morning, with the creation of light, that the world began; the distinction of day and night, and time too, began on a morning (Gen. 1:3-5, cf. 14:16, 18). The opposite conclusion has been drawn from the refrain which punctuates the story of creation: “There was an evening and there was a morning, the first, second, etc., day;.” This phrase, however, coming after the description of each creative work (which clearly happens during the period of light), indicates rather the vacant time till the morning, the end of a day, and the beginning of the next work… The change of reckoning must therefore have taken place between the end of the monarchy and the age of Nehemiah… This would bring us to the beginning of the [Babylonian] exile…”