The Pyramid Texts were funerary inscriptions that were written on the walls of the early Ancient Egyptian pyramids at Sakkara.
These date back to the fifth and sixth dynasties, approximately the years 2350-2175 B.C.E. However, because of extensive internal evidence, it is believed that they were composed much earlier, circa 3000 B.C.E.
The Pyramid Texts are, therefore, essentially the oldest sacred texts known.
Samuel Mercer was the first to produce a complete English translation of this mysterious text, in 1952. This was also the first complete translation in any language. The Mercer translation was followed by the R.O. Faulkner translation in 1969, which is considered the standard today.
However, this does not diminish the usefulness of Mercer's version, particularly because it has fallen into the public domain and is now available freely online here at sacred-texts, the first complete version of the Pyramid Texts on the Internet.