American Tract Society Bible Dictionary
The phrase "three days and three nights," Matthew 12:40 , was equivalent in Hebrew to the English "three days;" the Jews employing the expression "a day and a night" to denote our "day" of twentyfour hours. Nor did "three days," 1 Samuel 30:13 , literally "this third day," according to their usage, necessarily include the whole of three days, but a part of three days, a continuous period including one whole day of twenty-four hours, and a portion of the day preceding it and the day following it. Compare Genesis 7:12,17 1 Samuel 30:12-13 .
These files are public domain and are a derivative of the topics are from American Tract Society Bible Dictionary published in 1859.
Rand, W. W. Entry for 'Three'. American Tract Society Bible Dictionary. https://www.studylight.org/dictionaries/eng/ats/t/three.html. 1859.