While people can pray every day, God only blessed and sanctified the seventh day Sabbath and set aside as holy for worship because in it God had rested from His creative work “And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made” (Genesis 2:1–3). And in Exodus, God gives the same reason for blessing the seventh day “…For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it…” (Exodus 20:8–11).
As we continue to move forward in history, God’s children had more instruction in Leviticus: “Six days shall work be done: but the seventh day is the sabbath of rest, an holy convocation; ye shall do no work therein: it is the sabbath of the LORD in all your dwellings” (Leviticus 23:3). The word “convocation” is from the Hebrew word miqrâ’ (מקרא), which means a public meeting, assembly, or gathering. Here God calls for an assembly on the Sabbath. Thus, the Sabbath is a day of worship not just rest.
And in Isaiah, we clearly find that the Sabbath was indeed a day of worship, “It shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD” (Isaiah 66:23).
“And when the sabbath day was come, he began to teach in the synagogue: and many hearing him were astonished, saying, From whence hath this man these things? and what wisdom is this which is given unto him, that even such mighty works are wrought by his hands?” (Mark 6:2).
“When they departed from Perga, they came to Antioch in Pisidia, and went into the synagogue on the sabbath day, and sat down” (Acts 13:14).
“He reasoned in the synagogue every sabbath, and persuaded the Jews and the Greeks” (Acts 18:4).
For more on the Sabbath, please check the following link:
In His service,