The prophetic vision turns back the wheel of history to the very beginning of the relationship between God and the Israelites. While it reveals how their initial covenant was formed, it also carries a harsh rebuke for ancient sins. This uncovers a historical secret: God's anger over the nation's transgressions was suppressed and hidden for nearly nine hundred years, from the days of Egypt until the era of Ezekiel. For generations, His love covered their failures. However, as their sins multiplied over time, that ancient resentment was finally reawakened [רש"י, רד"ק].
The moment God chose the nation occurred while they were still in Egypt [שטיינזלץ, מצודת דוד], marked by the day He first sent His prophets to them [רד"ק]. This selection was driven by two parallel motives. On one level, the great spiritual leaders of the generation were chosen for their own intrinsic spiritual merit. On another level, the masses of the people were chosen by virtue of the covenant made with the Patriarchs and their good deeds [מלבי"ם, נחל שורק, חומת אנך].
To solidify this bond, God swore an oath [שטיינזלץ, רד"ק] guaranteeing their Exodus from Egypt [מצודת דוד]. This act fulfilled the ancient promise He had made to Abraham, Isaac, and Jacob [מלבי"ם, רד"ק]. Following this promise, a profound Divine revelation took place [שטיינזלץ], manifesting when the Divine Presence rested upon the prophets Moses, Aaron, and Miriam [מצודת דוד, רד"ק].
God then made a definitive declaration, which served as an oath in its own right, establishing the Israelites as His people [שטיינזלץ, רד"ק]. This meant that God Himself would be their direct leader and guardian, setting them apart from the other nations of the world, which are guided by intermediary celestial forces [מצודת דוד]. Ultimately, this revelation in Egypt was designed to remind the Israelites of their ancient bond with God [מלבי"ם] and inspire them to accept His authority anew. By taking upon themselves this renewed commitment, they were able to be redeemed earlier than the timeline originally decreed, escaping before they could completely assimilate into Egyptian culture [חומת אנך].