वेदान्त पारिजात सौरभ (भगवद् निम्बार्काचार्य - द्वैताद्वैत वेदान्त ब्रह्मसूत्र भाष्य सटीक)

[sū. 4. 2. 18.
830 VEDĀNTA-PĀRIJĀTA-SAURABHA ADH. 10.]
We reply: The knower proceeds by following the rays alone, in
accordance with the assertion "Then through those very rays he
goes up" (Chānd. 8.6.5). That there are rays during night too is
ascertained from the heat that is then experienced. During winter,
however, no heat is experienced during night, it being overpowered
by frost. Further, that there is a natural connection between the
vein and the rays is declared by Scripture thus: "Now, just as a long
road goes to two villages, this one and the yonder, so do the rays of
the sun go to the two worlds, this one and the yonder. They stretch
out from the yonder sun and creep into these veins. They stretch
out from these veins and creep into the yonder sun" (Chānd. 8.6.2).
Hence, it is established that there is a fixed rule that on his upward
progress, the knower follows the rays of the sun.
Here ends the section entitled "Following the rays" (9).
Adhikaraṇa 10: The section entitled "The
night". (Sūtra 18)
SŪTRA 18
"IF IT BE OBJECTED THAT DURING NIGHT, NOT, (WE REPLY.) NO;
ON ACCOUNT OF THE RELATION LASTING TILL THE BODY DOES, AND
(SCRIPTURE) SHOWS."
Vedānta-pārijāta-saurabha
It is not to be said that there is "no" attainment of the Highest
by a knower who dies "during the night". Owing to the cessation
of his connection with karmas, "lasting till the body does", he can
indeed attain Him, in accordance with the scriptural text: "For him
there is delay only so long I am (= he is) not free. Then I shall (= he
will) ¹ attain (Brahman)" (Chānd. 6.14.2 ²).
Vedānta-kaustubha
Now the problem, whether one who dies at night attains the
Highest Brahman or not, is being considered.
¹ Vide V.K. 1.1.7. ² R, ŚK.