In this translation, the text quoted below exists about 10% of the way through the text, towards the end of the first chapter ("1. Purification of the Buddha-Field"), a few paragraphs before the start of the secod chapter ("2. Inconceivable Skill in Liberative Technique"):
Thereupon, magically influenced by the Buddha, the venerable Sariputra had this thought: "If the buddha-field is pure only to the extent that the mind of the bodhisattva is pure, then, when Sakyamuni Buddha was engaged in the career of the bodhisattva, his mind must have been impure. Otherwise, how could this buddha-field appear to be so impure?"
The Buddha, knowing telepathically the thought of venerable Sariputra, said to him, "What do you think, Sariputra? Is it because the sun and moon are impure that those blind from birth do not see them?"
Sariputra replied, "No, Lord. It is not so. The fault lies with those blind from birth, and not with the sun and moon."
The Buddha declared, "In the same way, Sariputra, the fact that some living beings do not behold the splendid display of virtues of the buddha-field of the Tathagata is due to their own ignorance. It is not the fault of the Tathagata. Sariputra, the buddha-field of the Tathagata is pure, but you do not see it."
Then the Brahma Sikhin said to the venerable Sariputra, "Reverend Sariputra, do not say that the buddha-field of the Tathagata is impure. Reverend Sariputra, the buddha-field of the Tathagata is pure. I see the splendid expanse of the buddha-field of the Lord Sakyamuni as equal to the splendor of, for example, the abodes of the highest deities."
Then the venerable Sariputra said to the Brahma Sikhin, "As for me, O Brahma, I see this great earth, with its highs and lows, its thorns, its precipices, its peaks, and its abysses, as if it were entirely filled with ordure."
Brahma Sikhin replied, "The fact that you see such a buddha-field as this as if it were so impure, reverend Sariputra, is a sure sign that there are highs and lows in your mind and that your positive thought in regard to the buddha-gnosis is not pure either. Reverend Sariputra, those whose minds are impartial toward all living beings and whose positive thoughts toward the buddha-gnosis are pure see this buddha-field as perfectly pure."
I hope you'll get a better sense of it if you read that whole first chapter.