
“Beware how you take away hope from any human being.”
Oliver Wendell Holmes, Sr., in his valedictory address to medical graduates at Harvard University (10 March 1858), published in The Boston Medical and Surgical Journal Vol. LVIII, No. 8 (25 March 1858), p. 158; this has also been paraphrased "Beware how you take away hope from another human being".
Misattributed