The pasuk in Bamidbar 20:14-21 records Moshe's message to Edom as attributing the Shemot simply to a messenger whom Hashem sent — וַיִּשְׁלַח מַלְאָךְ וַיֹּצִאֵנוּ מִמִּצְרַיִם — conspicuously without invoking the "mighty hand" (יד חזקה) that appears in other Shemot formulations.
That language of "mighty hand" is precisely what marks other accounts of the Shemot: Devarim 26:8 declares that "GOD freed us from Egypt by a mighty hand, by an outstretched arm and awesome power, and by signs and portents," and Shemot 13:9 similarly enshrines the phrase כִּי בְּיָד חֲזָקָה הוֹצִאֲךָ יְהֹוָה מִמִּצְרַיִם as the very memorial of the event — making Moshe's omission of this language before Edom all the more deliberate.
the Bekhor Shor (Bamidbar 20:14) explains that Israel was seeking to win Edom's compassion by speaking the way one recounts one's troubles to a beloved kinsman, hoping Edom would take it to heart and show mercy — a rhetorical strategy that illuminates why Moshe softened and abbreviated the account.
Rabbeinu Bachya (Bamidbar 20:14) adds a theological dimension: Moshe invoked the brotherhood of Esav and Yaakov as sons of Avraham, noting that the decree of Egyptian bondage had originally applied to both, and that since Esav's departure had shifted the full burden onto Yaakov alone, the least Edom could do was allow Israel to pass — framing the appeal to kinship obligation rather than to displays of divine power.
the Chizkuni (Bamidbar 20:14) notes that the account here and its parallel in Devarim complement each other, with details present in one that are absent in the other — providing the broader hermeneutical context that no single telling of this episode is complete, and that the omission of the yad chazaka in Moshe's diplomatic speech to Edom must be read against the fuller picture preserved elsewhere.