Midrasch zu Schemot 34:4

On the seventh day after the Ten Commandments Moshe went up on the mountain, as it says "The Presence of the LORD abode on Mount Sinai, and the cloud hid it for six days..." (Shemot 24:16) This was in order for Moshe to purify himself. "On the seventh day He called to Moses from the midst of the cloud." (ibid.) "Moses went inside the cloud and ascended the mountain; and Moses remained on the mountain forty days and forty nights." (Shemot 24:18) On the 17th of Tammuz he came down and shattered the tablets, "The next day Moses said to the people, “You have been guilty of a great sin. Yet I will now go up to the LORD; perhaps I may win forgiveness for your sin.” Moshe went back up on the 18th of Tammuz and pleaded for mercy on behalf of Israel, as it is written "When I lay prostrate before the LORD those forty days and forty nights, because the LORD was determined to destroy you," (Devarim 9:25) At that moment, the Holy One once again viewed Israel with favor and said to Moshe to carve new tablets and to come up the mountain once again, as it says "Thereupon the LORD said to me, “Carve out two tablets of stone like the first, and come up to Me on the mountain; and make an ark of wood." (Devarim 10:1) He came down on the 28th of Av and carved the second tablets, as it says "So Moses carved two tablets of stone, like the first, and early in the morning he went up on Mount Sinai..." (Shemot 34:4) He went back up on the 29th of Av and the Torah was repeated to him a second time, as it says "I had stayed on the mountain, as I did the first time, forty days and forty nights; and the LORD heeded me once again: the LORD agreed not to destroy you." (Devarim 10:10) 'As I did the first time,' just as the first was a time of favor, so too the second were a time of favor- we can derive from this that those in the middle were a time of anger. He came down on the 10th of Tishre, which was Yom Kippur, and announced to them that they had found favor before God (Hamakom), as it says "Pardon our iniquity and our sin, and take us for Your own!” (Shemot 34:9) Therefore it was established as a fixed day and a remembrance for the generations, as it says "This shall be to you a law for all time: to make atonement for the Israelites for all their sins once a year..." (Vayikra 16:34)

(Fol. 86a) R. Ada b. Ahaba said: "Moses ascended [Mt. Sinai] early in the morning and descended early the [next] morning. He ascended early in the morning, as it is written (Ex. 34, 4.) And Moses rose up early in the morning, and went up unto Mt. Sinai; he descended early in the morning, as it is written (Ib. 19, 24.) Go, get thee down, and then shall thou come up, thou, and Aaron with thee. We compare the Yerida (descent) to the Aliya (ascent); just as the ascent was made early in the morning, so also was the descent made early in the morning." (Ib. b) Our Rabbis taught: "On the sixth day of the month [Sivan] the ten commandments were given to Israel. R. Jose said: 'On the seventh day of the month.'" "All agree," said Raba, "that on the first day of the month the Israelites arrived at the wilderness of Sinai, for it is written (Ex. 19, 1.) On this day they came into the wilderness of Sinai; and it is written there (Ib. 12, 2.) This month (Nisan) shall he unto you the chief of the months. [We draw an analogy from the word Haze (this) used in both places]; just as in the latter instance the word Haze (this) refers to the first of the month [as it plainly says], so does it also in the former instance refer to the first of the month; and furthermore all agree that the Torah was given to Israel on the Sabbath, for it is written here (Ex. 20, 8.) Remember the Sabbath day to keep it holy. and it is written there (Ib. 13, 3.) And Moses said unto the people remember this day, etc. [We derive by drawing an analogy from the words zachor (remember) used in both places]; just as in the latter case, zachor (remember) alludes to the very day of their coming out of Egypt, so also does it allude in the former case to the very day of Sabbath. The Rabbis and R. Jose differ though as to what day was the first of that month. R. Jose is of the opinion that the first of that month was set on the first day of the week, and that on this day no commandments were given because the Israelites were tired from their long journey. On the second day of the week the Lord said to them (Ib. 19, 6.) And ye shall be unto me a kingdom of priests. (Fol. 87a) On the third day [of the week] He warned them to keep away from the mount; on the fourth, to keep apart from the wives [three days, until the Sabbath]. But the Rabbis are of the opinion that the first of that month was set on the second day of the week; that on this day no commandments were given them because the Israelites were tired from their journey. On the third day [of the week] the Lord said unto them (Ib. ib. ib.) And ye shall be unto me a kingdom of priests. On the fourth, He warned them to keep away from the mount. On the fifth, to keep apart from their wives [two days, until the Sabbath]." The following objection was raised: And sanctify them to-day and to-morrow (Ib. ib.). This contradicts the opinion of R. Jose [who says that three days were set aside for sanctification]. R. Jose might explain it that Moses added one day upon his own recognizance, as it is taught: "Three things did Moses do upon his own authority, and the Holy One, praised be He! sanctioned them: Moses added one day [of separation] upon his own authority; he separated himself from his wife, and he broke the Tablets." He added one day upon his own authority; what verse did he interpret [to induce him to add one day]? Today and to-morrow, were in the Lord's commandment. To-day must be equal (in duration) to to-morrow; just as to-morrow includes day and night, so also must to-day include the day and night; the night, however, having already passed, so another day (a third) must be added in order to make up for the lost night. Whence do we learn that the Holy One, praised be He! agreed with him? Because the Shechina did not appear [on Mt. Sinai] until the Sabbath morning. And he separated himself from his wife, what verse did he interpret [to guide him in his action]? He applied the order given to Israel [to separate themselves from their wives] to himself, through the measure of the rule drawn from minor to major, thus saying: "If Israel with whom the Shechina did not converse but once at a certain time, is commanded by the Torah to separate themselves from their wives, I, with whom the Shechina converses constantly without having an appointed hour, should most certainly then separate myself from my wife." And whence do we learn that the Holy One, praised he He! agreed with him? It is written (Deu. 5, 27.) Go, say to them, return ye unto your tents, and immediately following, it is written: But as for thee, remain thou here with me. According to others, the sanction of God is derived from (Num. 12, 8.) Mouth to mouth do I speak with him. He broke the Tablets. What verse did he interpret [to guide him in his action]? He said to himself: "If concerning the Passover sacrifice, which is only one of the six hundred and thirteen commandments, it is said in the Torah (Ex. 12, 43.) No stranger shall eat thereof, how much more then should this be applied to the entire Torah considering that all Israel were apostates?"' Whence do we learn that the Holy One, praised be He! sanctioned this act? It is said (Ib. 34. 1.) Which thou didst break, whereupon Resh Lakish said: "It means 'Thanks for having broken it.'" Come and learn! And they shall he ready for the third day (Ib. 19, 11). Is this not in contradiction to R. Jose's interpretation? [According to him, it should have been on the second day.] We have already explained that Moses added one day upon his own recognizance. Come and learn! We are taught: "The third (day) of the third month and on the third day of the week." Does this not contradict the opinion of the Rabbis? The Rabbis might say this Baraitha is in accordance with the opinion of R. Jose.

Rabbi Tachanah said: The tables (of the Law) were not created out of the earth but out of the heavens, the handicraft of the Holy One, blessed be He, as it is said, "And the tables, the work of God were they" (Ex. 32:16). They are the tables which were of old, "and the writing" was divine writing; that was the writing which was of old, "graven upon the tables." Do not read Charuth, "graven," but (read) Chêruth, "liberty." When the Holy One, blessed be He, said to Moses: "Hew thee two tables of stone like unto the first" (Ex. 34:1), a quarry of sapphires was created for Moses in the midst of his tent, and he cut them out (thence), as it is said, "And he hewed two tables of stone like unto the first" (Ex. 34:4). Moses descended with the tables, and spent forty days on the mountain, sitting down before the Holy One, blessed be He, like a disciple who is sitting before his teacher, reading the Written Law, and repeating the Oral Law which he had learnt.