קבלה על נדה 61:36

23. The sefirot have both revealed and concealed aspects. The revealed is considered external, and the concealed, internal. An example of the concealed aspect is a kindness done in secrecy in which the kindness or goodness is not recognized, as stated in Proverbs: "Good is a revealed rebuke coming from a hidden love," and as stated in Talmud, "The recipient of a miracle does not recognize it as such."