Offers of eating until full for a fixed amount

Question:
He says: Honorable Shaykh, may Allah grant you success, some restaurants offer deals called "eat until full" for twenty riyals. What is the ruling on this action?

Answer:
This is unknown. This is not permissible. Eating until full is unknown. People differ in what constitutes being full. This sale is not permissible. I told you that most people today do not live except on risks and unknowns, and they consider this to be a source of earnings. This is not permissible. The Prophet (peace and blessings be upon him) forbade gharar (excessive uncertainty in a contract). He forbade risk-taking. He forbade gambling. In fact, the Qur'an forbids maysir (gambling). Therefore, transactions are not permissible unless they are clear and contain no ignorance or gharar. These are the sales of Muslims.