Canonical Reference: Dhp 165 Verified Source

“By oneself alone is evil done; by oneself is one defiled. By oneself is evil avoided; by oneself alone is one purified. Purity and impurity depend on oneself; no one can purify another.”

— Gautam Buddha
The Awakened One, Founder of Dhamma
Historical Setting & Context:

Pali Canon: Dhammapada 12.165 (Attanā'va kataṁ pāpaṁ, attanā saṅkilissati; Attanā akataṁ pāpaṁ, attanā'va visujjhati. Suddhī asuddhī paccattaṁ, nāñño aññaṁ visodhaye).