This story is about Mann and salwa. When Sayyiduna Musa عَلیہِ السلاَم was living along with six hundred thousand people of the Bani Israel in the field of Teeh. Allah عزوجل descended two heavenly feasts for them from the sky. One of which was ‘Mann’ and other was ‘Salwa’.
Mann was a type of halvah (sweet dish) resembling white honey or it may actually have been white honey. That descended from the sky every day in the form of rain. Salwa was cooked quails that would descend from the sky with the southerly wind. Whilst stating the blessings bestowed upon the Bani Israel, Allah عزوجل has stated in the Glorious Quran:
It was commanded by Sayyiduna Musa عَلیہِ السلاَم to eat Mann and Salwa on daily basis and not to preserve or store for next day at all.
Weak Faith of Some Peoples about descend Mann and salwa
But some people bearing weak faith became worried that if Mann and Salwa do not descend someday, then we will be left to starve to death in the plains of this field where no signs of food and water exist. Therefore, they began to secretly preserve some of the food for the following day.
As a consequence of disobeying the Prophet, the food they stored rotted and the blessings of Mann and Salwa stopped. That’s why the Holy Prophet ﷺ said that ‘had the Bani Israel not existed, neither food would get spoiled nor would meat have rotten’. The decay of food and meat rotting started since then. Otherwise, prior to that event, neither food would spoil nor would meat rot.
(Tafseer Ruh-ul-Bayan; part 1, Surah Al-Baqarah, verse 57)