By accident today I came across a supposed quotation of Eusebius, used in a negative way.
Eusebius, in AD 324, wrote, “We have transferred the duties of the Sabbath to Sunday.” Who are the “we”? Certainly not the apostles. They could not do so after the testament was ratified by the death of the Testator on the cross. When Eusebius says, “We have transferred the duties of the Sabbath to Sunday,” it reminds us again of what Paul foretold about those who, after his death, would speak “perverse things, to draw away disciples after them.” (Acts 20:30.) This last quotation from these early Fathers is dated AD 324. 
I always want to see a reference when I hear something like this. Walker doesn’t provide one, and a search for the phrase brings up only copies of his book. I’m not sure what group he wrote for, in truth.
The most accessible work by Eusebius has always been the Church History, so it’s probably in there. But a search through the ANF version, online, in all 10 books for “sabbath”, brings up no such words.