Ignatius 110 A.D. wrote in his epistle to the Magnesians 9
" If they who were concerned in old things, arrived at a newness of hope, no longer observing the Sabbath, but living according to the Lords day, by which our life sprung from him and by his death (whom certain persons deny)
we have been made his disciples, let us live according to Christianity."
Barnabas 120A.D. "Wherefore, also, we keep the eighth day with joyfulness, the day, also, on which Jesus rose again from the dead"
Justin Martyr 140 A.D. "Sunday is the day on which we all hold our common assembly, because it is the first day on which God, having wrought a change in the darkness, made the world; and Jesus Christ our savior , on the same day rose from the dead."
Didache 80-90 A.D. "And on the day of our lords resurrection, which is the Lords day meet more diligently."