גבורי כח עושי דברו לשמוע בקול דברו. שהקדימו נעשה לנשמע. אם כי בוודאי יש לבטוח ולהאמין כי לא יצוה הש”י רק אשר יהי’ בכחם. אך כי קבלו על עצמם לזכות לשמוע ע”י המעשה. וזה הקדמת נעשה לנשמע. וזהו עושי דברו. כי הנה בכל מעשה יש כח דבר ה’. כמ”ש בדבר ה’ שמים נעשו כו’ כל צבאם. וכשעושין המעשים כראוי זוכין לשמוע הקול שהוא למעלה מהדיבור. כמ”ש בזוה”ק. ומובן גם לכל אדם כי הקול בפנימיות מהדיבור. שמתחלק לפרטי דברים. והנה בנ”י זכו במעשיהם וקבלת מלכותו. לשמוע קול הש”י. וזה ג”כ זכור ושמור בדיבור אחד. ומי שישנו בשמירה ישנו בזכירה. כי שמירה צריך בבחי’ דיבור הנ”ל שנעלם תוך מעשה בראשית. וכפי השמירה זוכין לזכירה הוא מקום שא”צ שמירה כנ”ל:
In Tehillim (103:20) we find, “… גִבֹּרֵי כֹחַ עֹשֵׂי דְבָרוֹ לִשְׁמֹעַ בְּקוֹל דְבָרוֹ/… strong warriors who do His bidding, in order to hearken to the sound of His word.” It would seem that this pasuk is worded backwards. One needs to hearken to God’s word and understand what He requires of us in order to do His bidding. The pasuk states in reverse order – strong warriors do His bidding in order to hearken to his word. What does this mean?
Chazal teach that the strong warriors in this pasuk refer to the malachei hashareis/ministering angels and yet we find the same construct when we accepted the Torah. Just as the angels first agree to do God’s bidding before knowing what that bidding is, Chazal praise the nation of Israel for learning from the angels. When offered the Torah we responded, “… נַעֲשֶׂה וְנִשְׁמָע/… We will do and we will listen.” (Shmos 24:7) We were committed even before we knew what God required of us.
This needs an explanation, though. We certainly trusted in God and believed that He would not require us to do anything beyond our capabilities. We certainly knew that anything God would ask of us would be for our own benefit. Why the great praise, therefore, when we committed to comply with God’s commandments even before understanding them fully?
The Sfas Emes explains that while the simple meaning of listening to God’s word is understanding how to perform his commandments, it also implies something much deeper. God’s דִבּוּר/speech teaches us how to perform the commandments. However, the קוֹל דְבָרוֹ/sound of his word mentioned in the pasuk in Tehillim implies a deeper understanding. There is speech and there is the underlying sound that comprises speech. The underlying sound suggests the underlying spiritual meaning of the words. The Zohar makes this distinction between דִבּוּר/speech and קוֹל/sound as well when it refers to speech as components of sound (i.e. sound is the כְּלַל /general term; speech is the פְּרַט/specific term)
At Mount Sinai we committed to comply with God’s commandments and we accepted the yoke of Heaven upon ourselves in order to merit hearing the sound of God’s voice within the commandments, as it were, to experience the underlying spirituality that the manifests as speech. By committing to do whatever God required of us we would merit understanding that which would otherwise be impossible to attain. This is the reason we said, “נַעֲשֶה וְנִשְׁמָע /We will do and we will listen.” We committed to do in order to merit hearing (the underlying sound of God – understanding the inner meaning of the commandments and experiencing the underlying spirituality.) This is also the reason the pasuk in Tehillim states first, “עֹשֵי דְבָרוֹ/do His bidding” and only afterwards, “לִשְמֹעַ בְּקוֹל דְבָרוֹ/to hearken to the sound of His word.” Even the angels, by committing first to do, would merit hearing the sound within His words; they would merit understanding and experiencing the deeper meaning of their actions.
 Shabbos 88a
 For more detail on this Zohar and the relationship between קול/sound and דיבור/speech see the Sfas Emes on Shmos 5631 Second Ma’amar from “Undifferentiated sound”. Also, for a fascinating exposition on this concept as it relates to the names of God, the Tetragrammaton and Adnus and the different sounds we are required to blow with the Shofar on Rosh HaShanah see Ya’aros Devash Chelek 1 Derush 6.
 Zohar 2:3a
Sfas Emes blog