Commitment and Patience

The Commitment and Patience was a Covenant warship of unknown classification. It was mentioned in the Conversations from the Universe booklet included with the special edition of Halo 2.

It was in contact with the Covenant battlecruiser Sacred Promise and its fate was recorded on the black box of that ship.

The Sacred Promise requested fighter support from the Commitment and Patience. However a projectile hit the vessel and ruptured a fuel cell, instantly vaporizing the Sacred Promise. It is unknown what the two vessels were engaging, but it is possibly a UNSC vessel with its Magnetic Accelerator Cannon that destroyed the ship.

Classification Conjecturalization
The fact that the  carried fighters suggests that Commitment and Patience was a capital ship, perhaps a Reverence-class Cruiser or a Carrier.