In his lesson on the 4th Commandment dated July 20, 2011, pastor Jack Hibbs of Calvary Chapel Chino Hills, California, quoting Harry A. Ironside as an authority, claims that (beginning 8 minutes into the sermon):
"There are some religious groups, like the Seventh Day Adventists, that view the Sabbath as the day of worship, the day on which you should attend church for a worship service. While these groups typically also teach that no work is to be done on the Sabbath, the concept of the 'day of worship' is sometimes emphasized more than the 'day of rest.' The problem with this is that the Bible nowhere commands that the Sabbath is an actual day of worship as stated in Exodus 20:8-11, and the keeping of it being holy, separate or set apart. Other scriptures command against working on the Sabbath, but say nothing that the Sabbath being the ordained of God day for worship. ... In the Old Covenant dispensation, there was not one day set aside for worship, for sacrifices were made daily at the tabernacle / temple and “worship” was to be continually. The idea that the Sabbath day is the God-ordained day of corporate worship is, in fact, not biblical."
I beg to differ. It is most certainly biblical.
Lev 23:1 (KJV) And the Lord spake unto Moses, saying,
2 Speak unto the children of Israel, and say unto them, Concerning the feasts of the Lord, which ye shall proclaim to be holy convocations, even these are my feasts.
3 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.

Isaiah 66:23 (KJV) And 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.

The seventh day Sabbath of the fourth commandment is declared by the Lord to be a convocation day. It is to be a day that the people of God come together corporately. For what purpose? To worship the Lord as Creator:

Rev 4:11 (KJV)  Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.

Rev 14:6 (KJV) And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people,
7 Saying with a loud voice, Fear God, and give glory to him; for the hour of his judgment is come: and worship him that made heaven, and earth, and the sea, and the fountains of waters.
12 Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus.
The seventh day Sabbath was indeed set apart from the other days, sanctified and blessed by the Lord for a holy purpose:
Gen 2:3 (KJV) 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.

Ex 20:8 (KJV) Remember the sabbath day, to keep it holy.
9 Six days shalt thou labour, and do all thy work:
10 But the seventh day is the sabbath of the Lord thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
11 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.
1 John 2:3 (KJV) And hereby we do know that we know him, if we keep his commandments.
4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.
5 But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him

Sunday is NOT the biblical Sabbath day.
Did the Apostles Keep Sunday To Honor The Resurrection?
Offering Strange Fire Before The Lord.
The Seal of God in the Old and New Covenants.
The Sabbath, Creation, and the New Earth.
The 3 Angel's Messages.