B.G 2.13

देहिनोऽस्मिन्यथा देहे कौमारं यौवनं जरा। तथा देहान्तरप्राप्तिर्धीरस्तत्र न मुह्यति ॥ २-१३॥

dēhinō'sminyathā dēhē kaumāraṁ yauvanaṁ jarā। tathā dēhāntaraprāptirdhīrastatra na muhyati ॥ 2-13॥

[dēhinaḥ = the dweller of the body; asmin yathā dēhē = in the changing body; kaumāraṁ = childhood; yauvanaṁ = youth; jarā = old age; tathā = similarly, so also; dēha antara prāptiḥ = also one gets another body; dhīraḥ tatra na muhyati = it does not perturb the brave man.]

The dweller of the body experiences childhood, youth and old age in the changing body. So also one gets another body (after death). It does not perturb the brave man.

Gīta Tātparya 2.13

Changing the body after death is no different compared to changing the body from youth to old-age. Using the word 'dehina' Krishna excludes his own body, as the body of God does not undergo change.

मम स्वकीयदेहान्तरप्राप्तिरपि नास्तीति दर्शयितुं देहिन इति विशेषणम्। भवदादीनां सा भविष्यतीत्यपि शोको न कर्तव्यः। देहस्येदानी- मप्यन्यथात्वदर्शनात् ॥ १३ ॥

mama svakīyadēhāntaraprāptirapi nāstīti darśayituṁ dēhina iti viśēṣaṇam। bhavadādīnāṁ sā bhaviṣyatītyapi śōkō na kartavyaḥ। dēhasyēdānī- mapyanyathātvadarśanāt ॥ 13 ॥

[mama svakīyadēhāntaraprāptirapi = Myself (Krishna being God) getting different bodies of my own; nāstīti darśayituṁ = is denied, to show; dēhina iti viśēṣaṇam = the adjective ‘dehina' is used; bhavadādīnāṁ sā = Even if you and others; bhaviṣyatītyapi = get different bodies; śōkō na kartavyaḥ = they should not grieve; dēhasya idānīm apī anyathātvadarśanāt = Similar to body undergoing changes in current life when observed scientifically;]

Krishna used the adjective 'dehina', your body, to deny himself, the God, different bodies. Even if Arjuna and others get different bodies, they should not grieve. Because it does not differ from the body undergoing changes in current life when observed scientifically.