וְהָיָה֙ בַּיּ֣וֹם הַשִּׁשִּׁ֔י וְהֵכִ֖ינוּ אֵ֣ת אֲשֶׁר־יָבִ֑יאוּ וְהָיָ֣ה מִשְׁנֶ֔ה עַ֥ל אֲשֶֽׁר־יִלְקְט֖וּ י֥וֹם ׀ יֽוֹם׃ (ס)
And it shall come to pass on the sixth day that they shall prepare that which they bring in, and it shall be twice as much as they gather daily.’
Read kabbalistic (mystical) interpretation of Exodus 16:5: and classical mystical sources.