In the scriptures, a day is reckoned from evening to evening. The Israelites, the Jews and Jesus all reckoned a day in that way.
Here that reckoning of a day from evening to evening was applied to the sabbath of the Day of Atonement by God ...
"It shall be unto you a sabbath of rest, and ye shall afflict
your souls: in the ninth day of the month at even, from
**even unto even,** shall ye celebrate your sabbath."
The weekly Sabbath is from the sunset of the sixth day (Friday) to sunset of the seventh day (Saturday). That is the day Jesus kept holy. People call the Sabbath "a delight" when they love their Creator with all their hearts.
"If thou turn away thy foot from the sabbath,
from doing thy pleasure on my holy day;
and call the sabbath a delight,
the holy of the LORD, honourable;
and shalt honour him, not doing thine own ways,
nor finding thine own pleasure,
nor speaking thine own words:
Then shalt thou delight thyself in the LORD;
and I will cause thee to ride upon the high places of the earth,
and feed thee with the heritage of Jacob thy father:
for the mouth of the LORD hath spoken it."
Isa 58:13-14 (KJV)
To the mocker who will ask: What if you live at the North Pole? Our response is:
We observe the sabbath when the sun sets on the sixth day where we live. If we ever move to the North Pole, the Holy Spirit will teach us how to make suitable adjustments for that latitude.
"And the dragon was wroth with the woman,
and went to make war with the remnant of her seed,
WHICH KEEP THE COMMANDMENTS OF GOD,
AND HAVE THE TESTIMONY OF JESUS CHRIST." Rev 12:17 (KJV)