The answer to this is actually quite simple, they viewed:
- Every Wednesday as a little Ash Wednesday and therefore a day of fasting.
- Every Friday as a little Good Friday (Friday of the Passion of Our Lord) and therefore a day of fasting.
- Every Saturday is The Sabbath, and is therefore a day of fasting from work to honour YHVH our Father.
- Every Sunday is a little Yom HaBikkurim (Pescha / Easter) and is therefore a feast day in honour of the resurrection of Yeshua (Jesus).
Therefore, do not be fooled into believing that Sunday is The Sabbath; it never has been and never will be. Saturday has always been The Sabbath. In the book of Acts the Apostles gathered on the Sabbath to go over the Torah and Haftorah, and sometimes stayed into the next day, Sunday, discussing how Yeshua’s teachings, what would eventually become The New Testament (The Second Witness / Brit HaDasha), revealed the truth of the Torah, and brought its commandments to their fullness. A fitting thing to start discussing at sunset on the weekly anniversary of his death on the cross (the Sabbath starts Friday at sunset), through the Sabbath, and continue discussing into the weekly anniversary of his resurrection, until he comes again.