The Sheep Letter^[1] (Faroese: Seyðabrævið, Old Norse: sauðabréfit) is the oldest surviving document of the Faroe Islands. It is a royal decree enacted on 28 June 1298 by Duke Haakon, who later became King Haakon V of Norway. It deals principally with sheep husbandry, but also deals with other matters and functioned as a kind of constitution, removing most administrative power from the local Thing to the king and his representatives. It was drafted on the advice of Erlend, Bishop of the Diocese of the Faroe Islands in Kirkjubøur and of Sjúrður, Lawspeaker of Shetland, whom Duke Haakon had sent to the Faroes to consider the deficiencies in the agricultural law.^[2]

In contrast to the Færeyinga saga from Iceland, the Sheep Letter is written on the Faroe Islands and hence gives a better description of the Faroese society at that time. It also shows some early changes that the Faroese language had gone through from Old Norse.

The letter is preserved in two copies; one in the National Archives of the Faroe Islands in Tórshavn^[3] and one in the library of Lund University, Sweden.