Saubhagya Laksmi Upanishad is one of the minor Upanishads and is part of the Rig Veda.
Identifying the finite with the infinite,
The fragments with the Whole, one meditates
On the vast Source; thus fulfilment found
One becomes immortal.
Just as when salt mixes with water, it takes up the form of water, in the same way Samadhi (trance) means the mind merging into the cosmic soul (God).
When a living being’s material desires come to an end, and the living being and God march in one direction, that state is called Samadhi (trance). Samadhi is that balanced state of the soul wherein one’s agitations are nullified.
Saubhagya Lakshmi Upanishad