@MarcusMASTO @futurebird That particular quote is (slightly rearranged) from R. Rami Shapiro's interpretive translation of Pirkei Avot, "Wisdom of the Jewish Sages : A Modern Reading of Pirke Avot" (p. 41, 1993) --
The elaboration on it "Do justly now. Love mercy now. Walk humbly now."
is likely derived from Micah, where it appears as "You have been told, mortal, what is good,
And what GOD requires of you: Only to do justice, And to love goodness, And to walk modestly with your God" ( https://www.sefaria.org/Micah.6.8?lang=bi )
with the crucial ", now."s being likely from R. Hillel's famous quote from Pirkei Avot I "He also used to say: If I am not for myself, who is for me? But if I am for my own self alone, what am I?
And if not now, when?" ( https://www.sefaria.org/Pirkei_Avot.1.14?lang=bi ).
R. Tarfun's original quote, that this is an interpretive translation of, is translated directly as the second sentence and is from Pirkei Avot II:
https://www.sefaria.org/Pirkei_Avot.2.16?lang=bip