Seeing soap signifies wealth that will come into one's possession.
Seeing oneself wash something with soap and cleanse it of dirt and rust signifies recovery from illness, repentance from sin, deliverance from grief and sorrow, and release from debt.
Seeing a piece of soap signifies a matter that the dreamer will present to an emir or judge. Since soap removes dirt and impurity, seeing soap signifies the departure of grief and sorrow.