Song by William Byrd (1543-1623). It is based off of the Latin text for Psalm 115:1, and is also presumed to be the motto of the Knights Templar. The lyrics follow as:

Non nobis Domine, non nobis, sed nomine Tuo da gloriam.
Not unto us, O LORD, not unto us, but unto thy name give glory. (King James Version)

It was recently made popular with the production of Henry V, where Patrick Doyle came up with another score based on Byrd's earlier.

Non nobis Domine
Non nobis Domine, Domine
Non nobis Domine
Sed nomine, sed nomine
Tuo da gloriam
(repeat ad inifinitum)