God promises a safe landing but not a smooth passage.

Related:

• Don't salt other people's food. --
  Bulgarian...
• At the narrow passage there is no brother and no friend
  Arab...
• The worse the passage the more welcome the port.
  English...
• If you let everyone walk over you, you become a carpet.
  Bulgarian...
• Smooth seas do not make skillful sailors. --
  African...
• Promises are like the full moon: if they are not kept at once they diminish day by day.
  German...
• Pray to God, but keep rowing to shore. --
  Russian...