At daybreak Night, sent away for the Sun's rising, yields her place to Dawn, who comes with a bright child. The two are kin, immortal, following each other on a common unending path taught by the gods, different in colour and one in mind. Dawn opens the doors, wakes every creature to its own pursuit, causes the fire to be kindled, and does not wake the dead. She is last of the dawns gone and first of those to come; those who saw earlier dawns are gone and others will see her after us. The poet cries, Arise, life has returned. Another hymn says the sister leaves her place to her elder sister and looks on her before going.
East India · Bihar, Jharkhand, eastern Uttar Pradesh, NepalFolk
On the sixth day of the bright half of Kartik those keeping the waterless Chhath fast stand in the river with bamboo baskets of fruit and thekua and offer arghya to the setting sun; before the next sunrise they return and offer to the rising sun, then break the fast. The explanation given is that the Sun has two wives who are his powers: Pratyusha, the last ray, receives the evening offering and Usha, the first ray, the morning one. Chhathi Maiya is called Usha by some and the Sun's sister, protector of children, by others.
What is different here:
The pair is first light and last light, both wives of the Sun; Night is not named and the evening is honoured first.
From Night's side: when Night comes she sets her sister Dawn in her place. The Atharvaveda asks Night, as mother, to hand the sleepers to Dawn, Dawn to hand them to Day, and Day to hand them back to Night.
What is different here:
Told at evening and addressed to Night; adds the relay Night to Dawn to Day.
Sources: Hymns of the Rigveda, tr. R. T. H. Griffith (1896), hymns read for the Vedic layer; Relevance of Surya Puja and Chhath Vrat, The Sentinel (Assam), 6 November 2021; Chhath (Wikipedia); Chhath Puja (Sahapedia), Arnab Bhaumik; Chhath Puja, thanksgiving to the Sun God (MagikIndia); Atharva-Veda Samhita, tr. W. D. Whitney, rev. C. R. Lanman (Harvard Oriental Series 7-8, 1905), Book XIX hymns 47-50