In this hour of this day,
fill us, O Lord, with your mercy,
that rejoicing throughout the whole day,
we may delight in your praise;
through Jesus Christ our Lord.
Source: Sarum Breviary
Also found in Ancient Collects and Other Prayers, Ed. by W. Bright: J.H. & Jas. Parker, London, 1902 p. 13 #2
Also found here: http://www.ccel.org/ccel/potts/prayermiddle.x.pr99.html