Pa gur
Poem 31 of the Black Book of Carmarthen , a mid-13th century manuscript , is known from its first line as Pa gur yv y porthaur ? ( meaning "What man is the gatekeeper ? " ) or Pa gur , or alternatively as Ymddiddan Arthur a Glewlwyd Gafaelfawr ( "The dialogue of Arthur and Glewlwyd Gafaelfawr" ) . 
<triplet> Pa gur <subj> Black Book of Carmarthen <obj> part of