TT #32 · Parashas Vayeira · Passuk 18:17
And Hashem said, “Shall I hide from Avraham that which I am doing?”
Torah Temimah points to Yoma 38b. E-Daf · Sefaria — Yoma 38b
TT lemma: המכסה.
“Shall I hide…” Ravina said to a certain scholar: From where do the Sages derive the saying “The memory of a righteous person is for a blessing”? He replied: From the verse “Shall I hide from Avraham,” and immediately afterward it is written “And Avraham shall surely become a great nation.”
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. Adjacent verses supply the scriptural basis for the formula “zecher tzaddik livrachah.”
The memory of a righteous person is for a blessing; the source is the immediate linkage of Hashem’s consultation with Avraham to the promise that he will become a great nation.