That best portion of a good man’s life,
His little, nameless, unremembered acts
Of kindness and love.

William Wordsworth (1770-1850) English poet

“Lines Composed a few Miles above Tintern Abbey” (13 Jul 1798)
    (Source)

Often paraphrased into a sentence, e.g., "The best portion of a good man's life is his little, nameless, unremembered acts of kindness and of love."