I was asking if there was proof that the Apostles continued to observe a Saturday Sabbath while observing the Lord's Day.
Chapter and verse please so I don't have to work too hard finding it
While I may not use the word "observe". Below are 2 examples where the Apostle Paul still engaged the Jews on the Sabbath.
Acts 13:13-15 ESV
13Now Paul and his companions set sail from Paphos and came to Perga in Pamphylia. And John left them and returned to Jerusalem,
14but they went on from Perga and came to Antioch in Pisidia. And on the Sabbath day they went into the synagogue and sat down.
15After the reading from the Law and the Prophets, the rulers of the synagogue sent a message to them, saying, “Brothers, if you have any word of encouragement for the people, say it.”
So again, I am not saying they "kept" both for all time and in the same way. However, they did take advantage of the Jewish Sabbath to teach the Jews. Acts is definitely, in a few ways, a
TRANSITORY time for the Saints. Also see:
Acts 17:1-3 ESV
1Now when they had passed through Amphipolis and Apollonia, they came to Thessalonica, where there was a synagogue of the Jews.
2And Paul went in, as was his custom, and on three Sabbath days he reasoned with them from the Scriptures,
3explaining and proving that it was necessary for the Christ to suffer and to rise from the dead, and saying, “This Jesus, whom I proclaim to you, is the Christ.”
P.S. If anything I could see them keeping it at times, in order to not unnecessarily hinder their outreach to the Jews, not as a matter of moral law but for the conscience of the Jews (another example would be the circumcision of Timothy in Acts 16:3). I hope that is helpful and answers your question. There is no NT evidence that supports the required keeping of the Jewish Sabbath (Saturday) for Christians Post-Resurrection (in my opinion).