Isha upanishad is one of the primary upanishad contains the knowledge of god and universe. Isha upanishad contains the total 18 mantras or verses.

The sacred knowledge of god

The Ishopanishad on which all other Upanishads are based is the last chapter of the YajurVeda (Kanva Shakha or ascention), that is why the Upanishads are generally known by the name of the Vedanta, literally meaning the end or doctrine of the Vedas.