That Sunday is the sabbath is not the most typical answer I have found online from the Orthodox community.
I have found various answers online from the Orthodox community but this is what Wikipedia says:
Eastern Orthodoxy
Orthodox Sunday worship is not a direct Sabbath observance. The
Eastern Orthodox Church observes the first day (liturgical Sunday, beginning Saturday evening) as a weekly feast, the remembrance of Christ's resurrection, and a mini-
Pascha. As such, it tends to hold the first place within a week's observances, sharing that place only with other major feasts which occur from time to time. The Divine Liturgy is always celebrated, joining the participants on earth with those who offer the worship in God's kingdom, and hence joining the first day to the
eighth day, wherein the communion of the whole Church with Christ is fully realized. As such, it is never surpassed as a time for the Orthodox to assemble in worship.
The Church affirms its authority to appoint the time of this feast (and all observances) as deriving from the authority given to the apostles and passed to the bishops through the
laying-on of hands, for the sake of the governance of the Church on earth, and under the guidance of the Holy Spirit (
John 20:22,
John 14:26,
Rom. 6:14-18,
Rom. 7:6). It does not treat Sunday worship as a transference of Sabbath worship, but identifies the Sabbath, still on Saturday, as a Biblical "type", a precursor, realized fully only after Christ's fulfillment of the Mosaic Law (
Mat. 5:17-18). Thus, the Sabbath and the Mosaic Law both remain as a teacher, reminding Christians to worship in holiness, but now according to grace, in Christian observations and Sunday worship.
The grace received in baptism binds the Church to Christ, who has given his people the freedom to seek him directly in relationship, not to pursue whatever suits one's fancy. The goal of that freedom is always union with Christ in
theosis, and the maintenance of that union all the time, throughout this life and into the next, which is sometimes described as the "sanctification of time". Grace therefore never permits of whatever is sinful or unhelpful to salvation, such as laziness or hedonistic revelry. Rather, it becomes a stricter guide for behavior than any legal code, even the Mosaic, and disciplines the believer in some degree of ascetic endeavor (
Rom. 6:14-18).
[62]
Orthodoxy recognizes no mandated time for rest, a day or any other span, but the Church leads the individual to holiness in different ways, and recognizes the need for
economy and for rest. Activities such as sleep, relaxation, and recreation become a matter of balance and proper handling, and acceptance of God's mercy.
St. Basil the Greatexpresses thanks for this in a prayer often said by Orthodox Christians in the morning, after rising: "You do we bless, O Most High God and Lord of mercy, ... Who has given unto us sleep for rest from our infirmity, and for repose of our much-toiling flesh."
[63] In recognition of God's gifts, therefore, the Church welcomes and supports civil laws that provide a day away from labor, which then become opportunities for Christians to pray, rest, and engage in acts of mercy. In grace do Christians respond, remembering both the example of the Sabbath rest, and Christ's lordship (
Mk. 2:21-28).
