In The Holy Sabbath, A.W. Pink summarizes the reasons why Christians should observe the Sabbath on the first day of the week:
"First, because the day was clearly anticipated by Old Testament typology--the striking things connected with "the eighth day." Second, because the New Covenant necessitated a new day of rest to signify the old covenant was abrogated. Third, because the honour and glory of Christ required it: on the day specially appointed for divine worship, God would now have us occupied with His risen and exalted Son. Fourth, His own example bears witness thereto: His repeated meetings with His disciples (Joh 19) [sic] and His sending the Spirit on that day (Act 2:1) set His imprimatur upon it. Fifth, because the early Church so celebrated (Act 20:7; 1Co 16:1-2). There is not a single recorded instance in the New Testament of the saints meeting together for worship, after Christ's resurrection, on any other day but on the first day of the week! Sixth, because we are expressly told that God has "limited" or determined "another day" (Heb 4:9) than the old one, and that because we are divinely assured that, in view of the raising up of the rejected Stone to be the Head of the corner, "This is the day which the Lord hath made" (Psa 118:24), and therefore is it called "the Lord's Day in the New Testament (Rev 1:10)," (pp. 64-65).
"Then the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled for fear of the Jews, came Jesus and stood in the midst, and saith unto them, Peace be unto you," (John 20:19).