My quotes are these
"This is not your grave, but you are welcome in it" -Closing sentence, said on .
"I? I am a monument to all your sins." -Introducing himself, said on .
"This one is machine and nerve, and has its mind concluded. This one is but flesh and faith, and is the more deluded." -Said about the John-117 and then Thel 'Vadam, respectively, on Gravemind.
"There is much talk, and I have listened, through rock and metal and time. Now I shall talk, and you shall listen." -Said on Gravemind.
"This one's containment... (gestures to 2401 Penitent Tangent and growls and shudders a bit)... and this one's Great Journey... (gestures to the Prophet of Regret)... are the same. Your Prophets have promised you freedom from a doomed existence, but you will find no salvation on this Ring. Those who built this place knew what they wrought. Do not mistake their intent, or all will perish as they did before." -Said on Gravemind.
"If you will not hear the truth, then I will show it to you. There is still time to stop the key from turning, but first, it must be found. (gestures to John-117) You will search one likely spot... (gestures to Thel 'Vadam)... and you will search another. Fate had us meet as foes, but this Ring will make us brothers." -Said on Gravemind.
"Arrogant creatures! Your deaths will be instantaneous, while we shall suffer the progress of infinitude!" -Said on .
"We exist together now, two corpses in one grave..." -Said on High Charity.
"Silence fills the empty grave, now that I have gone. But my mind is not at rest, for questions linger on. I will ask, and you will answer." -To Cortana, after Halo 2's credits.