إِنَّ ٱللَّهَ فَالِقُ ٱلْحَبِّ وَٱلنَّوَىٰ … فَالِقُ ٱلْإِصْبَاحِ وَجَعَلَ ٱلَّيْلَ سَكَنًا وَٱلشَّمْسَ وَٱلْقَمَرَ حُسْبَانًا
"God is the splitter of the grain and the date-stone… He is the cleaver of the daybreak. He has made the night for rest, and the sun and the moon a measure of reckoning."
The root ف-ل-ق: to split, to cleave in two. The root was treated in al-Falaq in connection with the name of the sūra, and in al-Ṭāriq and al-Aʿlā.
The same verb: one the smallest thing in the palm of the hand, the other the whole horizon. I record this as my own reading: the verse joins the two scales with the same verb — the cracking of a seed and the breaking of dawn are named as the same work.
And at Fāṭir 35/1 it was treated that the root ف-ط-ر (to split) carries the same picture; I rely on that treatment. The two roots come from the same image.
وَجَعَلَ ٱلَّيْلَ سَكَنًا — the root س-ك-ن was treated at al-Fatḥ 48/4 (sakīna) and at al-Rūm 30/21 (li-taskunū ilayhā). And at al-Furqān 25/47 the night was named libās (a garment). Three sūras give the function of the night with three words: repose, garment, rest.
حُسْبَانًا — a measure of reckoning. Per the method (Method): I draw no conclusion about modern astronomy from this; the verse states that the sun and the moon are fit for the measuring of time — and this occurs in the same form at Yūnus 10/5.