וַיִּקְרָ֨א אֱלֹהִ֤ים ׀ לָאוֹר֙ י֔וֹם וְלַחֹ֖שֶׁךְ קָ֣רָא לָ֑יְלָה וַֽיְהִי־עֶ֥רֶב וַֽיְהִי־בֹ֖קֶר י֥וֹם אֶחָֽד׃ (פ)
빛을 낮이라 칭하시고 어두움을 밤이라 칭하시니라 저녁이 되며 아침이 되니 이는 첫째 날이니라
Rashi
כי בשש משה [AND WHEN THE PEOPLE SAW] THAT MOSES DELAYED LONG — Understand (בשש as the Targum does, as an expression denoting “lateness”.. Similar are: (Judges 5:28) “[Why is] his chariot so long (בשש) [in coming]?”; (Judges 3:25) “And they waited until it was late (עד בוש)”. For when Moses ascended the mountain he said to them (to the Israelites): at the end of a period of forty days (i. e. on the fortieth day) I shall return during the first six hours of the day (before noon). They thought that the day on which he ascended the mountain (the seventh of Sivan) was to be included in this number (thus — Sivan having 30 days — he was expected back before noon on the sixteenth of Tammuz). In fact, however, he had said to them “after forty days” meaning complete days — forty days, each day together with its night that precedes it — (as is the customary Jewish reckoning; cf. Genesis 1:5: ויהי ערב ויהי בקר). Now, as regards the day of this ascent, its night was not part of it that it can be reckoned as a complete day, for he ascended on the seventh of Sivan early in the morning (cf. Rashi on Exodus 19:3); it follows therefore that the fortieth day really fell on the seventeenth of Tammuz and not as the people had believed on the sixteenth. On the sixteenth of Tammuz Satan came and threw the world into confusion, giving it the appearance of darkness, gloom and disorder that people should say: “Surely Moses is dead, and that is why confusion has come into the world!” He said to them, “Yes, Moses is dead, for six hours (noon) has already come (בשש = בא שש) and he has not returned etc.” — as is related in Treatise Shabbat 89a (cf. Rashi and Tosafot there and Tosafot on Bava Kamma 82a ד"ה כדי). One cannot, however, say that they erred only on account of it being a cloudy day, their mistake consisting in not being able to distinguish between forenoon and afternoon, and that thus they were correct in their supposition that he was to return on the sixteenth of Tammuz; for this assumes that he really returned on the day when they made the calf, but that they were under the impression that noon was past — for, as a matter of fact, Moses did not come down until the following day (the day after they had made the calf), for it is said (v. 6) “And they rose up early in the morrow, and brought up burnt offerings”— and only after wards the Lord said to Moses (v. 7) “Go, go down; for thy people … have corrupted themselves”.
Kli Yakar
And Moses assembled all the congregation of the children of Israel, etc. Rashi explains [this happened] on the day after Yom Kippur, etc. And in the portion of Jethro it is written (Exodus 18:13), And it came to pass on the next day that Moses sat to judge the people, and Rashi explains there that this was the day after Yom Kippur. It seems to me that it is known that this assembly was to inform them about the commandment of the Tabernacle and the donations, as will be explained shortly. Moses was concerned lest one of them donate something to the Tabernacle that was not his own, thinking that he rightfully possessed it. This would be inappropriate for building this great and holy house from theft, [as it is written] in the place of justice, there is wickedness. Therefore, Moses first announced: “Whoever has a legal matter, let him approach me for judgment,” so that all the people would come to their place in peace, and each one would know what is his and what is not his through his judging between them. Then he would inform them about the matter of the donation, saying, “Take from yourselves a contribution to the Lord.” “From yourselves” means from what is yours and not from what belongs to your fellow, otherwise the phrase “from yourselves” would be superfluous. Although undoubtedly he could not judge all the people in one day, and even on that day he was not judging the entire day, for although it is said (Exodus 18:13) from morning until evening, this is as Rashi explains: anyone who judges a case with true justice is credited by Scripture as if he became a partner with the Holy One, blessed be He, in the work of Creation, as it is said (Genesis 1:5), And there was evening and there was morning. Otherwise, when would he have informed them about the making of the Tabernacle? Nevertheless, the donation was also not completed in one day, and perhaps he informed them that anything over which two people had a dispute should not be donated until the judgment was first clarified as to whom it belonged.
Or HaChaim
ויהי ביום השמיני, it was on the eighth day; We need to analyse why the Torah had to introduce this chapter with the word ויהי. We are told in Megillah 10 that Rabbi Levi claimed there was an ancient tradition that every time the word ויהי appears it has a connotation of something painful having occurred. This view was challenged by the questioner pointing to the word ויהי in our portion which introduces the joyous event of Aaron performing the rites in the Tabernacle; furthermore, we have a Baraitha according to which this day was as joyous an occasion as the day on which G'd created Heaven and Earth, a day which is also introduced in the Torah by the words ויהי ערב ויהי בקר, "it was evening it was morning, etc." The Talmud answers that the saddening event in our portion was the death of Nadav and Avihu. The questioner in the Talmud continues, wanting to know why the word ויהי is used in Kings I 6,1 when the building of Solomon's Temple is reported. He also points to Genesis 29,10 where Jacob's encounter with his bride-to-be Rachel is introduced by the word ויהי. The questioner mentions a further occurrence of that word every time G'd completed part of the creation of the universe and the Torah describes the completion of that portion with the words ויהי ערב ויהי בקר. What were the negative elements on those occasions which prompted the Bible to draw our attention to them by means of the word ויהי? Rav Ashi answers that the word ויהי by itself may have either positive or negative connotations. When the word ויהי is followed by the word בימי, "during the lifetime of, etc." it invariably has a negative connotation. The Talmud added that there are five occasions when the expression ויהי בימי occurs in the Bible. Thus far the discussion in Megillah 10.