This is the English language version of the original 10th Century Mozarabic hymn, Attende Domine, which is especially appropriate for Lent. Here it's led by George Curnow, Senior Cantor at the Church of St. Martin in Roath:
Here again, too, is TPL's page on this; they call it a "Mozarabic hymn from the 10th century."
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
To thee, Redeemer, on thy throne of glory:
lift we our weeping eyes in holy pleadings:
listen, O Jesu, to our supplications.
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
O thou chief cornerstone, right hand of the Father:
way of salvation, gate of life celestial:
cleanse thou our sinful souls from all defilement.
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
God, we implore thee, in thy glory seated:
bow down and hearken to thy weeping children:
pity and pardon all our grievous trespasses.
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
Sins oft committed, now we lay before thee:
with true contrition, now no more we veil them:
grant us, Redeemer, loving absolution.
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
Innocent captive, taken unresisting:
falsely accused, and for us sinners sentenced,
save us, we pray thee, Jesu, our Redeemer.
Hear us, O Lord, have mercy upon us: for we have sinned against thee.
Here again, too, is TPL's page on this; they call it a "Mozarabic hymn from the 10th century."