The Celtic liturgy appears to have attached importance to it; the Liber Hymnorum, a manuscript preserved at Trinity College, Dublin (E. 4, 2), gives two collects on the lines of the letter to Abgar.
Liturgi Keltik rupanya menganggap legenda itu penting; "Liber Hymnorum", sebuah naskah yang terlestarikan di Trinity College, Dublin (E. 4, 2), memuat dua koleksi baris-baris surat kepada Abgar.