Can a loan document that's already been paid back be used a second time for a loan?

How was Yaakov allowed to purchase the Birthright from Eisav if it was a "davar shelo bah l'olam"?

If someone gives someone a ride to their destination and at the end says pay me for the gas, are they required to pay given that the person was going anyway?

How did Avraham take ownership possession of Eretz Yisrael?

If someone finds a signed cheque on the ground, do they have to return it to the owner or the person it is written out to?

When a child is given a toy as a gift does it belong to them or their parent? What about a monetary gift?

Why the courtyard of a woman can receive on her behalf but the law is different for a man?

The rights of a worker to quit and the rights of an employee to fire his workers- we are servants only of Hashem

Can you become the owner over an ownerless item you find on Shabbat?

How to decide between 2 business partners - one who wants to sell the whole business and the other who wants to split the business and keep one half for himself?