תהלים, פרק קל״ב, פסוק ד׳

A profound commitment to achieving a meaningful goal is powerfully expressed through a severe oath to avoid all rest and quiet. Driven by this purpose, a person declares with absolute resolve that they will not allow themselves to sleep or enjoy any physical comfort beyond the absolute minimum necessary for basic survival [אבן עזרא, מצודת דוד, ביאור שטיינזלץ].

The language of this vow distinguishes between different levels of rest, contrasting regular, heavy sleep with a much lighter slumber. In this context, references to the eyelids are understood to point directly to the pupil of the eye [מצודת ציון, ביאור שטיינזלץ]. The primary approach among commentators is that these varying descriptions of rest are simply poetic repetition, emphasizing the exact same idea through different words [רד״ק, מצודת דוד].

However, other scholars find a more specific boundary within the vow. They argue that the oath does not demand total sleeplessness or completely forbid closing one's eyes. Instead, the focus is strictly on avoiding a regular, deep, and fixed routine of sleep [רד״ק, אלשיך]. Taking a uniquely specific approach, another perspective narrows the scope of the oath entirely, suggesting that the commitment is simply a pledge to avoid taking an afternoon nap [אבן עזרא].