The oldest papyrus found were Merer's journals.

An excerpt from the article 15 facts about Egypt

The documents of an official with this name date back 4.5 thousand years and describe plans to build a temple (perhaps the Pyramid of Cheops) and import sandstone (perhaps the pyramid's cladding).

The document also contains the original name of the pyramid - Akhet-Khufu, i.e. Horizon of Khufu (Cheops).