गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

"After he departs from the body, the soul travels on the sun's rays. Casting off
the material mind, and meditating on the sacred syllable Om, the soul travels to
the sun, which is the doorway to the worlds. They who are enlightened with
transcendental knowledge may enter that doorway, but they who are not
enlightened are stopped from entering. The following verse describes this: There
are a hundred and one nāḍīs . . . "
This means that after he passes through the nāḍī on the top of the head, the
enlightened soul travels on the path of the sun's rays.
Saṁśaya (doubt): Must the soul depart from the body during the daytime, or
may he also depart during the night (and still attain liberation)?
Pūrvapakṣa (the opponent speaks): Because during the night the rays of the sun
do not shine, the enlightened soul must depart from the material body only during
the daytime.
Siddhānta (conclusion): In the following words the author of the sūtras gives
His conclusion.
Sūtra 18
raśmy-anusārī
raśmi—rays; anusārī—following.
He follows the rays.
Purport by Śrīla Baladeva Vidyābhūṣaṇa
Whenever he dies, the enlightened soul is able to follow the rays of the sun.
This is so because the Śruti-śāstra gives no specific instruction in this regard.
Sūtra 19
niśi neti cen na sambandhasya yāvad deha-bhāvitvād darśayati ca
niśi—during the night; na—not; iti—thus; cet—if; na—not; sambandhasya—of
the relationship; yāvat—as long as; deha-bhāvitvāt—because of the existence of the
body; darśayati—reveals; ca—also.