अहिनिर्ल्वयनीनाशादहेर्नाशो यथा न हि ।देहत्रयविनाशेन नात्मनाशस्तथा भवेत् ॥ १८ ॥
In plain words
Destroy the skin a snake has shed and the snake is untouched. In just the same way, the three bodies can perish and the ātman does not perish with them.
Close to the Sanskrit
Just as, from the destruction of the snake's cast-off skin, there is indeed no destruction of the snake, so, by the destruction of the three bodies, no destruction of the Self would come about.