Theodore's years of exile, regular fasting, and exceptional exertions had taken their toll, and in 826 he became quite ill. In this year, he dictated his "Testament", a form of spiritual guidance for the future abbots of the Stoudios monastery, to his disciple Naukratios. He died on 11 November that year, while celebrating mass, apparently in the monastery of Hagios Tryphon on Cape Akritas in Bithynia. Eighteen years later, his remains, along with those of his brother Joseph, were brought back to the Stoudios Monastery, where they were interred beside the grave of their uncle Platon.