Gwyddit fy Nuw ond rhyfedd hyn

Gwyddit fy Nuw, (ond rhyfedd hyn),
  Fath fyddwn cyn fy ffurfio;
A pha fath fydda i bob dydd
  O'r amser sydd i'm dreulio.

A chwilia nghalon trwyddi'n lan,
  Agor hi o flaen dy wyneb;
Pa'm cadwaf fai 'ddiwrth un barhâ
  Yn frawd i dragwyddoldeb?

Mae'n dda im', fod fy na a'm drwg
  O fewn dy olwg beunydd;
I'th wydd mi ddeuaf yn ddinag,
  Ni 'mguddiaf rhag fy Arglwydd.

Rheola'm calon, Arglwydd cun,
  I ti dy hun mae'n perthyn;
Ar ei stafelloedd bob yr un,
  Gosod dy hun yn frenin.

Thou knowest my God, (but this wonder),
  What I would be before my forming;
And what I shall be every day
  From the time which is for me to spend.

And search my heart completely thoroughly,
  Open it before thy face;
Why shall I keep a fault from one who will continue
  As a friend for eternity?

It is good for me, that my good and my evil is
  Within thy sight daily;
To thy presence I shall come undeniably,
  I will not hide from my Lord.

Rule my heart, dear Lord,
  To thee thyself it belongs;
Over its chambers every one,
  Set thyself as king.