وَإِنَّ غَدًا وَإِنَّ الْيَوْمَ رَهْنٌ وَبَعْدَ غَدٍ بِمَا لَا تَعْلَمِينَا
Tomorrow, and even today, are held in pledge; what the day after tomorrow contains is something you do not know.
Rahn literally suggests something pledged or held as security. Applying it to time conveys that the future is not fully within human control. The ending bi-mā lā taʿlamīnā continues the address to a woman: she cannot know what subsequent days hold.