"ברוך אתה...לשמוע קול שופר"
“Blessed are you...to hear the sound of the shofar.”

QUESTION: Why is it customary to keep the shofar covered during the reciting of the berachot prior to the actual sounding of the shofar? (See Bei’ar Heiteiv 593:3)

ANSWER: Prior to the Akeidah — binding of Yitzchak to be an offering — it says, “And they came to the place of which Hashem had told him, and Avraham built the altar there” (Bereishit 22:9). The Midrash (56:5) asks, “And where was Yitzchak?” Rabbi Levi answered, “Avraham had taken and hidden him saying, ‘Lest Satan may endeavor to seduce him from obedience and willingness to allow himself to be sacrificed, or perhaps he will throw a stone at him, maiming him and disqualifying him from serving as a sacrifice.’ ”

Since the sounding of the shofar of a ram is so that Hashem remember for our sake the Akeidah (Rosh Hashanah 16a),to recall Avraham’s hiding Yitzchak before the Akeidah, we hide the shofar.

(קדמות הזהר)