Translation: "Lord Dong is not the only man of power in the empire."
Response in 189 to threats by Dong Zhuo. After this, Yuan Shao left the capital and began organising a coalition against Dong. This confrontation marked the end of the uneasy peace between the two. Source: "Xiandi Chunqiu" (獻帝春秋), page 190 of Sanguo Zhi (三國志).
Translation: "A real man should die in front of the ranks, not hide behind a wall!"
Statement in 191 at Battle of Jieqiao. Yuan Shao and his halberdsmen, surrounded by enemy cavalry, refuses to take refuge. He is said to have thrown off his helmet as he said this. Source: "Yingxiong Ji" (英雄記), page 193-194 of Sanguo Zhi.