Parashas Vayeira · Passuk 18:27
And Avraham answered and said, “Behold now, I have taken upon myself to speak to my Lord, though I am but dust and ashes.”
Torah Temimah points to Sotah 17a.
TT lemma: עפר ואפר.
English: “Dust and ashes.” Rava said: Why did the Torah say to bring dust for the sotah? If she is worthy, a son like Avraham our father will come forth from her, as it is written of him “I am but dust and ashes”; if she is not worthy, she returns to her dust.
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The ritual dust is linked both to reward and to potential punishment.
The dust used in the sotah ceremony alludes to Avraham: if the woman is innocent she may produce a son like him; if guilty she returns to dust.