Ramban on Exodus 32:6:1

וְטַעַם וַיֵּשֶׁב הָעָם לֶאֱכֹל וְשָׁתוֹ שֶׁיָּשְׁבוּ כֻּלָּם כְּאֶחָד לֶאֱכֹל לְשָׂבְעָה וְשָׁתֹה לְשָׁכְרָה, כַּאֲשֶׁר יַעֲשׂוּ בַּחַגִּים וּבַמּוֹעֲדִים, וְאַחֲרֵי כֵן קָמוּ לְצַחֵק בַּעֲצַבֵּיהֶם וּלְשִׂמְחָה, וְסִפֵּר זֶה בַּעֲבוּר מַה שֶׁאָמַר "קוֹל עַנּוֹת אָנֹכִי שֹׁמֵעַ" (שמות ל"ב:י"ח), כִּי מֹשֶׁה מְצָאָן מְשַׂחֲקִין לְפָנָיו, וַיִּגְבַּהּ לִבּוֹ בְּדַרְכֵי ה' לָקַחַת אוֹתוֹ מִלִּפְנֵיהֶם וּלְשָׂרְפוֹ לְעֵינֵיהֶם, וַיַּשְׁקְ אוֹתוֹ לָהֶם. וְהִשְׁלִים הַכָּתוּב כָּל מַה שֶׁעָשׂוּ בָּעֵגֶל, וְאַחַר כֵּן סִפֵּר מַה שֶׁאָמַר הקב"ה לְמֹשֶׁה "לֶךְ רֵד", אֲבָל הָיָה דִּבּוּר זֶה לְמֹשֶׁה בַּבֹּקֶר הַשְׁכֵּם כַּאֲשֶׁר הִשְׁתַּחֲווּ לוֹ וַיִּזְבְּחוּ לוֹ, וּבְרֶדֶת מֹשֶׁה יָשְׁבוּ לֶאֱכֹל וְלִשְׁתּוֹת וְקָמוּ לְצַחֵק, וּמְצָאָם בַּשְּׂחוֹק, וְגַם זֶה רְאָיָה לְמָה שֶׁפֵּרַשְׁתִּי (רמב"ן על שמות ל"ב:א'), שֶׁלֹּא נֶאֱמַר לְמֹשֶׁה לֶךְ רֵד כִּי שִׁחֵת עַמְּךָ בַּיּוֹם שֶׁעָשָׂה אַהֲרֹן הָעֵגֶל וְהַמִּזְבֵּחַ, שֶׁהָיָה יוֹרֵד מִיָּד, אֲבָל כְּשֶׁזָּבְחוּ וְהִשְׁתַּחֲווּ לוֹ הָעָם אָז אָמַר לְמֹשֶׁה שֶׁיֵּרֵד: AND THE PEOPLE SAT DOWN TO EAT AND TO DRINK. This means that they all sat down together to eat and drink inordinately, as they would do at feasts and on festivals, and afterwards they rose up to make merry with their idols and indulge in revelry. Scripture tells us this on account of what Moses [later] said, the noise of them that sing do I hear,³⁰²Verse 18. for Moses found them acting riotously in front of him and his heart was lifted up in the ways of the Eternal,³⁰³II Chronicles 17:6. to take it from before them and to burn it in their presence [and scatter its powder upon the water] and make them drink of it.
Now Scripture first completed the account of everything they had done with the calf, and afterwards told of what the Holy One, blessed be He, said to Moses, Go, get thee down.³⁰⁴Verse 7. This communication, however, was given to Moses early that morning, when they worshipped the calf and sacrificed to it. When Moses came down from the mountain they had sat down to eat and to drink, and rose up to make merry,³⁰⁰Verse 6. and he found them in revelry. This also is proof to what I have explained [that at first their intent was not to worship idols], since it was not said to Moses, Go, get thee down, for thy people have dealt corruptly³⁰⁴Verse 7. on the day that Aaron made the [golden] calf and the altar, [for had they been made for the purpose of idolatry, Moses] would have come down immediately. Instead, it was only when the people sacrificed to it and worshipped it that He told Moses to go down.