וָֽאֶתְנַפַּ֞ל לִפְנֵ֣י יְהוָ֗ה אֵ֣ת אַרְבָּעִ֥ים הַיּ֛וֹם וְאֶת־אַרְבָּעִ֥ים הַלַּ֖יְלָה אֲשֶׁ֣ר הִתְנַפָּ֑לְתִּי כִּֽי־אָמַ֥ר יְהוָ֖ה לְהַשְׁמִ֥יד אֶתְכֶֽם׃
So I fell down before the LORD the forty days and forty nights that I fell down; because the LORD had said He would destroy you.
Read halakhic rulings (Jewish law) on Deuteronomy 9:25: and classical halakhic sources.