Exodus 32:30

And it came to pass on the morrow, that Moses said unto the people, Ye have sinned a great sin: and now I will go up unto the LORD; peradventure I shall make an atonement for your sin.

And it came to pass on the morrow,.... The eighteenth day of Tammuz it was, the same writers say, that Moses implored the mercy of God for Israel. Jarchi on Exodus 32:11 says it was on the seventeenth day the tables were broke, on the eighteenth the calf was burnt, and on the nineteenth that Moses went up to intercede for them:

that Moses said unto the people, Ye have sinned a great sin; the sin of idolatry, see Exodus 32:21 from whence it appears, that all that were guilty of it were not slain, perhaps only some of one tribe; and there was great reason to fear, that as wrath was gone forth it would not stop here, but others would fall a sacrifice to the divine displeasure; wherefore it is proposed by Moses to make application to the Lord on their behalf, that they might obtain mercy:

and I will go up unto the Lord: on the top of Mount Sinai:

peradventure I shall make atonement for your sin; not by any sacrifice offered, but by his prayers prevail with God to forgive their sin, and not punish any more for it: he had by his first prayer obtained of the Lord not to consume them off of the face of the earth, and utterly destroy them as a nation; but that he did not hinder but that resentment might be shown in a lesser degree, or by parts; as not 3000 men had been cut off, chiefly out of one tribe, if not altogether, the rest of the tribes might expect to be visited, according to the number of their delinquents.