B.G 2.23
nainaṁ chindanti śastrāṇi nainaṁ dahati pāvakaḥ। na cainaṁ kledayantyāpo na śoṣayati mārutaḥ ॥ 2-23॥
Weapons cannot cut Him, fire cannot burn Him, water cannot drench Him, not even wind can dry Him.
Gīta Bhāshya 2.23
Both internal natural causes and external special causes cannot destroy the Lord
svataḥ prāyonimittaiśca avināśino'pi kenacinnimitta viśeṣeṇa syāt। kakacchedavat ityato viśeṣanimittāni niṣedhati– 'nainam' iti ॥ 23 ॥
It is indestructible because not only it cannot be destroyed by natural causes, originating from themselves, but also by particular external causes. By rejecting it can be pierced, the verse 'nainam' forbids the possibility of its destruction by special causes.
Gīta Tātparya 2.23
Various external cases cannot destroy the Lord
kāraṇatopi na īśvarasya anyathātvamityāha - nainaṃ chindantīti ॥23॥
The verse 'nainam chindanti', not possible to pierce, clarifies there is no destruction to the Lord by various external causes.