Writ of Union

Summary
The Writ of Union is an oath of service to the Covenant, written by the Prophets and Elites who created the Covenant. In the current Covenant tradition, when an Elite becomes a warrior, they recite the oath with a Prophet.

The Oath
In an extended cinematic found in the Halo 2: Limited Collector's Edition DVD, the Arbiter recites the first canto with the High Prophet of Truth:

Arbiter: "So full of hate were our eyes that none of us could see. Our war would yield countless dead but never victory."

Prophet of Truth: "So let us cast arms aside, like discard our wrath. Thou in faith will keep us safe, whilst we find the path."

This is also found in the inside cover of the Halo 2 soundtrack.

In The Arbiter, SpecOps Elites recite this:

SpecOps Commander: "When we joined the Covenant, we took an oath."

SpecOps Elites: "According to our station! All without exception!"

SpecOps Commander: "On the blood of our fathers, on the blood of our sons, we swore to uphold the Covenant."

SpecOps Elites: "Even to our dying breath!"

In an early draft of the Halo 2 script, the following quote appeared before the first cinematic:

On and on shall old war go, Without respite my blood will flow

O’er your eyes ‘til they cannot see The impossibility of victory.

--Excerpt from the Writ of Union Unknown Covenant Author