Ashtavakra Gita · Verse 1.18 · Ashtavakra speaks

Know that which has form to be unreal, and the formless to be permanent. Through this instruction in truth, rebirth becomes impossible.
साकारमनृतं विद्धि निराकारं तु निश्चलम् ।एतत्तत्त्वोपदेशेन न पुनर्भवसम्भवः ॥ १-१८॥
sākāram anṛtaṃ viddhi nirākāraṃ tu niścalam |etattattvopadaśena na punarbhavasambhavaḥ ||1-18||

Word by word

साकारम्

sākāram

that which has form, the formed

adjective, neuter, accusative singular

अनृतम्

anṛtam

unreal, false

adjective, neuter, accusative singular

Anṛta: the unreal — body, mind and all phenomena with form. They appear to exist but have no independent reality beyond the formless Self.

विद्धि

viddhi

know, realize

verb, imperative 2nd person singular, vid

निराकारम्

nirākāram

the formless, without form

adjective, neuter, accusative singular

निश्चलम्

niścalam

permanent, immovable, steady

adjective, neuter, accusative singular

तत्त्वोपदेशेन

tattvopadaśena

through instruction in truth/reality

compound noun (tattva + upadeśa), masculine, instrumental singular

Tattva: the truth or reality of the Self. Upadeśa: spiritual instruction from the guru. This verse concludes the essential teaching of chapter 1.

पुनर्भवसम्भवः

punarbhavasambhavaḥ

the possibility of rebirth

compound noun (punar + bhava + sambhava), masculine, nominative singular

Rebirth is caused solely by identifying the eternal Self with body, mind, etc. Self-knowledge destroys this identification and thereby ends the cycle of rebirth.