There are a lot of quotes that refer to the pride of Elizabeth and Darcy, you kind of have to infer the prejudice part though… I've included some of those quotes that speak about the pride of both Elizabeth and Darcy, as well as some other characters. These should help you formulate your argument, or expand your knowledge of the book, or whatever your purpose may be.
"I could easily forgive his PRIDE, if he had not mortified mine." (Elizabeth about Darcy; Ch. 5)
"Vanity and PRIDE are different things, though the words are often used synonymously. A person may be PROUD without being vain. PRIDE relates more to our opinion of ourselves, vanity to what we would have others think of us." (Mary; Ch. 5)
Elizabeth's astonishment was beyond expression. She stared, coloured, doubted, and was silent. This he considered sufficient encouragement; and the avowal of all that he felt, and had long felt for her, immediately followed. He spoke well; but there were feelings besides those of the heart to be detailed; and he was not more eloquent on the subject of tenderness than of PRIDE. His sense of her inferiority— of its being a degradation— of the family obstacles which judgement had always opposed to inclination, were dwelt on with a warmth which seemed due to the consequence he was wounding, but was very unlikely to recommend his suit.
"And this," cried Darcy, as he walked with quick steps across the room, "is your opinion of me! This is the estimation in which you hold me! I thank you for explaining it so fully. My faults, according to this calculation, are heavy indeed! But perhaps," added he, stopping in his walk, and turning towards her, "these offenses might have been overlooked, had not your PRIDE been hurt by my honest confession of the scruples that had long prevented my forming any serious design. These bitter accusations might have been suppressed, had I, with greater policy, concealed my struggles, and flattered you into the belief of my being impelled by unqualified, unalloyed inclination; by reason, by reflection, by everything. But disguise of every sort is my abhorrence. Nor am I ashamed of the feelings I related. They were natural and just. Could you expect me to rejoice in the inferiority of your connections?— to congratulate myself on the hope of relations, whose condition in life is so decidedly beneath my own?"
The tumult of her mind, was now painfully great. She knew not how to support herself, and from actual weakness sat down and cried for half-an-hour. Her astonishment, as she reflected on what had passed, was increased by every review of it. That she should receive an offer of marriage from Mr. Darcy! That he should have been in love with her for so many months! So much in love as to wish to marry her in spite of all the objections which had made him prevent his friend's marrying her sister, and which must appear at least with equal force in his own case— was almost incredible! It was gratifying to have inspired unconsciously so strong an affection. But his PRIDE, his abominable PRIDE— his shameless avowal of what he had done with respect to Jane— his unpardonable assurance in acknowledging, though he could not justify it, and the...