Arrogance often reveals itself most clearly in the way people speak. The wicked are portrayed as individuals whose offensive words recognize no boundaries, boldly crossing the vast space between heaven and earth. Their mouths are set firmly against the heavens [ביאור שטיינזלץ, מצודת דוד], pouring out a rushing stream of arrogant words [רד״ק]. The primary approach among commentators is that this highlights their sheer audacity in directing their speech upward to insult God and His angels [אבן עזרא, מצודת דוד]. They deny God's involvement in the world, claiming He is completely unaware of what happens below [רד״ק, מאירי], and they openly complain against His divine justice [אלשיך]. Taking a different perspective, [אבן עזרא] suggests that their pride is so extreme that they view their own words as absolute heavenly decrees, impossible to challenge or reverse.
This heavenly arrogance stands in sharp contrast to their actual physical reality. Even though they are merely earthly creatures living on the ground beneath the sky, they still dare to speak against God who dwells on high [רד״ק, מצודת דוד, אבן עזרא]. At the same time, their destructive speech does not remain pointed only at heaven; it lashes out to harm other people as well [ביאור שטיינזלץ, מאירי]. Their tongue acts like a spy roaming the earth, constantly searching for and publicizing the flaws of righteous individuals [אבן עזרא].
Beyond the personal pain they cause, their behavior creates a severe public danger. Their words of disbelief spread widely among the masses, influencing others to adopt their ways and begin questioning God's providence [אלשיך]. Looking at the broader severity of harmful speech, the Sages derive a powerful lesson about the destructive nature of gossip and slander. Even though the sin of speaking evil begins with a person standing firmly on the earth, the resulting guilt continues to grow and expand until it reaches all the way to heaven [תורה תמימה].