The oldest known copy of the Ten Commandments has recently been made available online by the Cambridge Digital Library. It is known as the Nash Papyrus and is 2,000 years old. From the article:
Before the Dead Sea Scrolls were found by a Bedouin shepherd in 1947, the “Nash Papyrus,” also called “The Ten Commandments,” was the oldest known manuscript containing a text from the Hebrew Bible. It gets its name from the Egyptologist Walter Llewellyn Nash who purchased the manuscript from an antiquities dealer in 1902.