He unleashed it upon them for seven nights and eight days, in succession. You could see the people destroyed in it, as if they were decayed palm trunks.
Translation endnotes
[69:7] The expression "seven nights and eight days" denotes a continuous period. From this expression, we might infer that the Quranic day starts from daylight rather than night, as is the case in Jewish tradition. Those who contend otherwise rely on the common Quranic usage of the word night before the word day, but they must also account for 91:3-4, where the day is mentioned before the night. The statement in verse 36:40, that night cannot pass the day, might implicitly support our position. Verse 2:187 describes the starting points of day and night. Verses 3:27 and 17:12, talk about the dawn and evening, the two overlapping periods between night and day. According to these verses, the night starts with the sunset and day ends with the disappearance of sun light from the horizon. Similarly, day starts at down and night ends with the sunset. Also, see 10:67; 25:62; 36:37.