Marcus Aurelius
Meditations 10.4
If a man is mistaken, instruct him kindly and show him his error. But if thou art not able, blame thyself, or blame not even thyself.
Marcus Aurelius, Meditations 10.4, translated by George Long
If a man makes a slip, enlighten him with loving-kindness, and shew him wherein he hath seen amiss. Failing that, blame thyself or not even thyself.
Marcus Aurelius, Meditations 10.4, translated by C. R. Haines