2:1 day of Pentecost. “Pentecost,” meaning “fifty days,” was a festival observed fifty days after the feast of firstfruits, which was held on a sabbath day. The feast of firstfruits (Leviticus 23:9-14) was actually prophetic of the resurrection of Christ (I Corinthians 15:20), which also had taken place on the first day of the week. Thus Pentecost was held on the first day of the week, and it was on such a day that the Holy Spirit came to indwell the church. Quite possibly this fact played a part in the gradual adoption by the churches of the first day of the week as their regular day of rest and worship (note Acts 20:7; I Corinthians 16:2). The weekly observance of the sabbath was in commemoration of the completion of God’s work of creation (Genesis 2:1-3; Exodus 20:8-11), but God’s great work of redemption was now also completed (John 19:30). Thus, by observing their weekly “sabbath day” (“rest day”) on the first day of the week, they would be honoring the completion of both God’s work of creation and His work of redemption. Pentecost also commemorated the giving of the law at Mount Sinai, which occurred fifty days after the Passover (Exodus 12:6; 19:1,11).