Is the sin of gambling considered usury (ribā)? And is it true that the least form of usury is for a man to commit adultery with his mother, and is this a simile or the same sin? And is it considered usury or gambling if a group of players agree that the loser will perform a certain strike?

Betting is of two types: permissible and forbidden. The permissible type is that which aids in Jihad, and the forbidden type is that which falls under gambling and games of chance. It is not usury (riba).

A hadith (definition) was narrated from the Prophet, peace and blessings be upon him, describing usury as seventy-three doors, the easiest of which is like a man marrying his mother. The worst form of usury is dishonoring a Muslim. This hadith illustrates the enormity of the sin of usury.

As for punishing the loser in a football match with beating or other forms of harm, it is forbidden because it harms a Muslim without any sin on their part.