The relationship between God and the Israelites is an absolute, eternal covenant, rooted in the very existence of the universe rather than shifting circumstances. To illustrate the unbreakable nature of this bond, the limits of human physical comprehension—the vast heavens and the deep earth—are used as the ultimate standard. The primary approach among commentators views this as an impossible condition. Just as human beings are entirely incapable of measuring the height of the sky or fully exploring the deep foundations of the earth, God will never reject the Israelites. Despite all their past wrongdoings, He promises not to cast them away, but rather to forgive them [רד״ק, מצודת ציון].
The specific physical imagery carries distinct meaning. The concept of measuring is applied to the heavens because the sky appears stretched out and spread wide, naturally inviting the thought of measuring its vast height [רש״י, רד״ק]. Conversely, the earth represents the lowest point, acting as the bedrock for the entire structure of the world [רד״ק]. Exploring its foundations refers to reaching the deepest, innermost point—the very center of the earth [מצודת ציון, אברבנאל].
Beyond the physical impossibility, the contrast between heaven and earth holds deeper significance. One perspective suggests that God’s love for Israel is infinite in two distinct ways. First, it has no quantitative limit, much like the immeasurable heavens. Second, the underlying reason for this love is impossible to fully comprehend or investigate, just like the hidden depths of the earth. Because this profound connection is intrinsic and does not rely on logical conditions, it cannot be undone by human failings. While sins have a set limit and measure, the bond with God is endless [מלבי״ם].
Taking a different approach, the division between the heights above and the depths below can be seen as a reflection of the people's wrongdoings. The heavens above symbolize the sins committed directly against God, while the foundations of the earth below represent the offenses committed between people. Ultimately, even the heavy accumulation of both types of transgressions will never cause God to abandon the Israelites [אברבנאל].