Devarim 9:18

18 And I fell down before Hashem, as at the first, arba’im yom and arba’im lailah; I did neither eat lechem, nor drink mayim, because of kol chattatchem ye sinned, in doing wickedly in the sight of Hashem, to provoke Him to anger.

Devarim 9:18 Meaning and Commentary

Deuteronomy 9:18

And I fell down before the Lord
In prayer for Israel who had sinned; but this he did not immediately after he had broken the tables, but when he had first ground the calf to powder, strewed it on the water, and made the children of Israel drink it; and when he had chided Aaron, and ordered the sons of Levi to slay every man his brother:

as at the first forty days and forty mights;
which is to be connected, I think, not with what goes before; for we read not that he fell down before the Lord, at the first time he was with him so long in the mount; but with what follows: "I did neither eat bread nor drink water"; as he neither ate nor drank the first forty days, so neither did he these second forty; see ( Deuteronomy 9:9 )

because of all your sins which ye sinned, in doing wickedly in the
sight of the Lord, to provoke him to anger;
for they were guilty of more sins than one; besides idolatry, they were guilty of unbelief, ingratitude which were notorious and flagrant, were done openly and publicly, in sight of his glory and majesty on the mount; all which must be very provoking to him, and on account of these Moses prayed and fasted.

Devarim 9:18 In-Context

16 And I looked, and, hinei, ye had sinned against Hashem Eloheicha, and had made you an egel massekhah (a molten calf); ye had turned aside quickly out of HaDerech (The Way) which Hashem had commanded you.

17 And I took the shnei haluchot, and cast them out of my two hands and broke them before your eyes.

18 And I fell down before Hashem, as at the first, arba’im yom and arba’im lailah; I did neither eat lechem, nor drink mayim, because of kol chattatchem ye sinned, in doing wickedly in the sight of Hashem, to provoke Him to anger.

19 For I was afraid of the anger and hot displeasure, wherewith Hashem was angry against you to destroy you. But Hashem listened unto me at that time also.

20 And Hashem was very angry with Aharon to have made him shmad; and I davened on behalf of Aharon also at that time.