The unique bond between God and the Israelites functions like a sacred agricultural law. When a farmer harvests his crops, he separates the first and best portion as a holy offering. Similarly, the Israelites were set apart from all other nations to be God's sacred portion, representing the finest among the peoples [ביאור שטיינזלץ, מצודת דוד, מצודת ציון]. This status is akin to the very first grain harvested or the sacred food given to the priests, which is strictly forbidden for anyone else to consume [רש״י, צאינה וראינה, רד״ק, ביאור שטיינזלץ].
The emergence of this sacred harvest is deeply tied to the Israelites' journey. They are viewed as the first crop to miraculously grow from a dry, barren desert that had never produced anything before [מלבי״ם]. By walking through an unsown land, they were sustained by Manna from heaven. This spiritual food sanctified them and proved their elevated rank. They were treated as honored servants eating directly from their Master's table, protected from harm, rather than lowly slaves who could be mistreated without consequence [אדרת אליהו]. This sacred status remained pure, rooted in their experience at Mount Sinai where they were renewed and devoted themselves to God with love [נחל שורק].
Because the Israelites are considered a holy offering, a severe warning protects them. Just as an outsider who eats sacred priestly food incurs a heavy penalty, any nation that attacks, robs, or oppresses the Israelites will bear deep guilt and face strict punishment [רש״י, רד״ק, מצודת דוד, צאינה וראינה]. There is a profound distinction between a regular sin and this specific guilt. Guilt reflects an internal reality where the soul recognizes it deserves retribution for its flaws. To ensure this consequence is fully realized, the punishment extends beyond the spiritual realm and manifests as a tangible, physical disaster [מלבי״ם].
The primary approach among commentators is that even when God uses other nations as an instrument to punish the Israelites for their own wrongdoings, those attacking nations will ultimately face severe consequences for the harm they inflicted. God remembers the enduring merit of the Patriarchs to protect His people, a reality proven historically by the spectacular downfalls of foreign conquerors like Sennacherib and Nebuchadnezzar, King of Babylon [רד״ק, מצודת דוד]. This guarantee of protection and ultimate justice is sealed as the absolute, unchanging decree of God [מצודת דוד].