But (בּוּת, H956) is an Aramaic verb meaning to pass the night, to lodge, to spend the night. It appears in the Aramaic portions of Daniel (Daniel 6:18), describing King Darius spending a sleepless night after throwing Daniel into the lions' den. Related to the Hebrew lin or lun (H3885), this Aramaic form carries the specific sense of passing a night in a particular state — often in anxiety, vigil, or waiting.
The single occurrence of but in Daniel 6:18 is theologically loaded: Darius the Mede spent the night fasting, without entertainment, unable to sleep — consumed with anxiety over Daniel's fate. This is the pagan king, the most powerful man in the known world, lying awake while Daniel — the man he condemned — sleeps peacefully in the lions' den (Psalm 4:8). The sleeplessness of the powerful and the peace of the righteous is a recurring biblical motif. Psalm 3, written during Absalom's rebellion, declares: 'I lie down and sleep; I wake again, because the LORD sustains me.' The contrast between Darius' restless night and Daniel's presumed calm illustrates the interior peace that comes from trust in God versus the inner torment of those who govern by human power alone.