And after eight days again - That is, on the return of the first day of the week. From this it appears that they thus early set apart this day for assembling together, and Jesus countenanced it by appearing twice with them. It was natural that the apostles should observe this day, but not probable that they would do it without the sanction of the Lord Jesus. His repeated presence gave such a sanction, and the historical fact is indisputable that from this time this day was observed as the Christian Sabbath. See Acts 20:7; 1 Corinthians 16:2; Revelation 1:10.
Related Commentaries of John 20:26
John 20:26
26 And after eight days again his disciples were within, and Thomas with them: then came Jesus, the doors being shut, and stood in the midst, and said,Peace be unto you.