O Lord God of truth.@Psalm 31:5
Ambrose of Milan (340-397)

At­trib­ut­ed to Am­brose of Mi­lan (cir­ca 340-397) (Rec­tor po­tens, ver­ax De­us); trans­lat­ed from La­tin to Eng­lish by John M. Neale in The Hymn­al Not­ed, 1852.

Fer­i­al, Sar­um mel­o­dy (MIDI, NWC, PDF).

John M. Neale (1818-1866)

O God of truth, O Lord of might,
Who orderest time and change aright,
Brightening the morn with golden gleams,
Kindling the noonday’s fiery beams.

Quench Thou in us the flame of strife,
From passion’s heat preserve our life,
Our bodies keep from perils free,
And give our souls true peace in Thee.

Almighty Father, hear my cry
Through Jesus Christ our Lord most high,
Who with the Holy Ghost and Thee
Doth live and reign eternally.