ירמיהו, פרק ה׳, פסוק ב׳

The outward display of religious devotion does not always reflect a sincere heart. Often, the language of faith is hijacked to mask deception. People may publicly take oaths in God's name, but this should not be mistaken for genuine belief [ביאור שטיינזלץ]. In their daily lives, the people typically swear by other gods. When they suddenly choose to invoke God's name, it is merely a performance to present themselves to the outside world as loyal and God-fearing individuals [רד״ק, אברבנאל].

In reality, they deliberately use God's name precisely when they intend to lie [מצודת דוד]. It is an absolute certainty that their oaths are entirely false [מנחת שי]. This hypocrisy becomes especially destructive in financial disputes and conflicts between neighbors. Taking a solemn oath in a courtroom might give the illusion of a fair justice system and a society rooted in faith. Beneath this surface, however, the oath serves as a weapon for extortion and theft. By using God's name to validate a falsehood, a person essentially proves that they are a heretic who completely denies His existence [מלבי״ם].

Ultimately, God assigns no value to the empty words spoken from their lips. He looks past the external performance to examine the true faith within the heart, fully aware of the deception hiding behind their lies [רד״ק, אברבנאל].