וַיָּבֹ֥א מֹשֶׁ֛ה בְּת֥וֹךְ הֶעָנָ֖ן וַיַּ֣עַל אֶל־הָהָ֑ר וַיְהִ֤י מֹשֶׁה֙ בָּהָ֔ר אַרְבָּעִ֣ים י֔וֹם וְאַרְבָּעִ֖ים לָֽיְלָה׃ (פ)
And Moses entered into the midst of the cloud, and went up into the mount; and Moses was in the mount forty days and forty nights.
Read halakhic rulings (Jewish law) on Exodus 24:18: and classical halakhic sources.