Tirukkural 807: Familiarity

Those who have (long) stood in the path of affection will not give it up even if their friends cause (them) their ruin.

Image of Satguru Sivaya Subramuniyaswami
Observe those who are steadfast. You will learn from them. Observe those who are not, and they, too, will teach you. They will teach what you should not do.
—Gurudeva