Isaiah 17:9-11 (KJV)
9 In that day shall his strong cities be as a forsaken bough, and an uppermost branch, which they left because of the children of Israel: and there shall be desolation.
10 Because thou hast forgotten the God of thy salvation, and hast not been mindful of the rock of thy strength, therefore shalt thou plant pleasant plants, and shalt set it with strange slips:
11 In the day shalt thou make thy plant to grow, and in the morning shalt thou make thy seed to flourish: but the harvest shall be a heap in the day of grief and of desperate sorrow.
Isaiah 17
What Happens To People Who Disregard God?
If you forget the God of your salvation and die, then in death fear will set in. Even grief and sadness for where you will go next.