مُّطْمَئِنَّة

Appears 2 times in the Quran. (Root: طمن)
  1. And Allah sets forth a parable: (Consider) a town safe and secure to which its means of subsistence come in abundance from every quarter; but it became ungrateful to Allah's favors, therefore Allah made it to taste the utmost degree of hunger and fear because of what they wrought.

  2. O soul that art at rest!