Genesis 7:12

“And the rain was upon the earth forty days and forty nights, etc.] So long it was falling upon it, after the windows of heaven were opened. Aben Ezra would have it, that all things were in such confusion, during the flood, that there was no difference between day and night, since, it is said, “day and night shall not cease any more”; and that after the waters ceased, then Noah knew that forty days and nights had passed, for God had revealed this secret to him; but the text seems more to make against him than for him.”

“- XXV. The Flood The date is here given, at which the flood commenced and the entrance into the ark was completed. “In seven days.” On the seventh day from the command. “In the second month.” The primeval year commenced about the autumnal equinox; we may say, on the nearest new moon. The rains began about a month or six weeks after the equinox, and, consequently, not far from the seventeenth of the second month. “All the fountains of the great deep, and the windows of the skies.” It appears that the deluge was produced by a gradual commotion of nature on a grand scale. The gathering clouds were dissolved into incessant showers. But this was not sufficient of itself to effect the overwhelming…”

“It rained without intermission or abatement, forty days and forty nights - And that upon the whole earth at once. Genesis 7:14”

“forty: Gen 7:4, Gen 7:17; Exo 24:18; Deu 9:9, Deu 9:18, Deu 10:10; Kg1 19:8; Mat 4:2 Genesis 7:13”