'Day' in the Bible

which has come to you. Indeed, just as in the whole world the gospel is constantly bearing fruit and spreading [by God’s power], just as it has been doing among you ever since the day you first heard of it and understood the grace of God in truth [becoming thoroughly and deeply acquainted with it].

For this reason, since the day we heard about it, we have not stopped praying for you, asking [specifically] that you may be filled with the knowledge of His will in all spiritual wisdom [with insight into His purposes], and in understanding [of spiritual things],

Therefore let no one judge you in regard to food and drink or in regard to [the observance of] a festival or a new moon or a Sabbath day.