TT #96 · Parashas Vayeira · Passuk 22:2
And He said, “Take, please, your son, your only one, whom you love, Yitzchak, and go to the land of Moriah, and offer him there as a burnt-offering on one of the mountains that I will tell you.”
Torah Temimah points to Sanhedrin 89b. E-Daf · Sefaria — Sanhedrin 89b
TT lemma: קח נא.
“Take, please.” Rabbi Shimon bar Abba said: “Na” is only a language of request. The Holy One, blessed be He, said to him, “I have tested you with several tests and you stood in them; now stand for Me in this test, so that they will not say there was no substance in the earlier ones.”
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The particle is read as a polite request that frames the severity of the trial.
God requested, rather than merely commanded, that Avraham take Yitzchak; the final test was needed so that earlier tests would not be dismissed as insubstantial.