TT #85 · Parashas Vayeira · Passuk 21:12
And God said to Avraham, “Let it not be bad in your eyes concerning the lad and concerning your maidservant; whatever Sarah says to you, listen to her voice, for in Yitzchak shall seed be called to you.”
Torah Temimah points to Megillah 14a. E-Daf · Sefaria — Megillah 14a
TT lemma: שמע בקולה.
“Listen to her voice.” This teaches that Sarah our mother was a prophetess.
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The instruction to obey establishes prophetic authority.
Sarah was a prophetess; Hashem Himself commanded Avraham to listen to her voice.