TT #38 · Parashas Vayeira · Passuk 18:19
For I have known him, in order that he may command his children and his household after him to keep the way of Hashem by doing righteousness and justice, so that Hashem may bring upon Avraham that which He has spoken concerning him.
Torah Temimah points to Kesubos 8b. E-Daf · Sefaria — Kesubos 8b
TT lemma: צדקה ומשפט.
“Righteousness and justice.” A certain translator opened and said: “Our brothers, performers of kindness, sons of performers of kindness, who uphold the covenant of Avraham our father, as it is said, ‘For I have known him… to do righteousness and justice.’”
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The verse is used as a liturgical and rhetorical proof-text for the trait of kindness.
Israel is addressed as “performers of kindness, sons of performers of kindness,” because Avraham was chosen precisely so that he would transmit the practice of tzedakah and mishpat.