Question: What are the forms of Gharar (uncertainty/deception) in sales?

Gharar (definition) is that which has an apparent aspect that deceives the buyer and an unknown inner aspect. It is a sale with an unknown outcome, and a cause for enmity, hatred, and injustice. The Prophet, peace and blessings be upon him, forbade Gharar sales, such as the sale of the 'Habl al-Habala' (the offspring of the offspring of a pregnant animal), fish in water, selling fruits before their ripeness becomes apparent, and the sales of Mulamasa and Munabadha. Imam Al-Nawawi said that the prohibition of Gharar sales is a great principle that includes the sale of a runaway slave, something non-existent, something unknown, something that cannot be delivered, something that the seller does not fully own, selling fish in abundant water, milk in the udder, selling a fetus in the womb, selling an unspecified portion of a heap, and so on. All of this is void because it involves Gharar without necessity.