O Arglwydd gosod rhag gair ffraeth

O Arglwydd, gosod rhag gair ffraeth,
  Gadwraeth ar fy ngenau:
Rhag im' gam-dd'wedyd, gosod ddor
  Ar gyfor fy ngwefusau.

gwelir: O brysia Arglwydd clyw fy llais

O Lord, set against a frivolous word,
  A guard on my mouth:
Lest I mis-speak, set a door
  On the edge of my lips.

3 From hasty language curb my tongue,
    and let a constant guard
  Still keep the portal of my lips,
    with wary silence barred.

see also:
Set on my mouth a seal O Lord
  Howell Elvet Lewis [Elfed] 1860-1953
  Sweet Singers of Wales 1889