Fat,
re: "Jewish laws of mourning, see the laws of 'shiva', for an example."
I looked at the Wikipedia article and didn't see anything regarding the OP. I wonder if you might explain why you think it is applicable?
I wonder if anyone has documentation that shows that a phrase stating a specific number of days as well as a specific number of nights was ever used in the first century or before when it absolutely couldn't have included at least a part of each one of the specific number of days and at least a part of each one of the specific number of nights?
May be this will help you out, but I doubt it.
Remember that the laws of Shiva were handed down orally from Rabbi to Rabbi, as part of the Oral Torah for 3300 years. Shiva is derived from Genesis 50:1-14
http://www.chabad.org/library/article_cdo/aid/281589/jewish/Computing-the-Shiva-and-Sheloshim.htmBurial at TwilightWhen burial occurs late in the day, provided it takes place before nightfall (i.e., even during the approximately eighteen minutes between sunset and dark: the legal duration of bein hashemashot, or twilight), mourning should begin at the cemetery, a short distance from the grave itself. The mourners remove their shoes and then seat themselves on a stone or railing. Thus, while it may already be nighttime when they arrive at the home where shiva will be observed, the law considers that mourning was formally begun during daylight at the cemetery.
That day is, therefore, counted as the first of the seven days of shiva. The mourners, however, should be informed that mourning technically began at the cemetery. (This is possible only if the mourner has not yet prayed the evening maariv service. If he has already prayed the service, shiva begins the next day.)
Thus, too, if one is notified of the burial of a relative at twilight, and he finds himself on the road, or in another public place, he should make formal mental note of the fact that his mourning has begun, and he is then permitted to count that day as the first of shiva, even though he was not able to remove his shoes and sit on the low bench-the formal recognition of shiva.
The Duration of ShivaThe seven days of mourning begin immediately after interment. They end on the morning of the seventh day after burial, immediately following the shacharit (morning) service. Those present extend condolences, and the mourner rises from his week of mourning. If no public shacharit service is held in the mourner's home shiva ends after the mourner has recited his private prayers, provided that it is after sunrise.
In computing the seven days, Jewish tradition follows the principle of considering a fraction of a day as a complete day.
Thus, the day of burial is considered as the first day, even though interment may have been concluded only a few moments before nightfall. Thus, too, the seventh day is considered a full day even though mourning was observed for only a short time after sunrise. Two fractional days of mourning are counted as two whole days of Shiva.To illustrate, if interment occurred on Wednesday, afternoon, Wednesday is the first day, Thursday the second, Friday the third, Saturday the fourth, Sunday the fifth, Monday the sixth, and Tuesday morning is the seventh and final day.
Also from the Pesachim 4a we see that that parrt of the day counts for the whole day.
For it is written, and in the eighth day the flesh of his foreskin shall be circumcised,and it was taught: The whole day is valid for circumcision,