What are the types of contracts?

There are many types of contracts (ʿuqūd), including what a person contracts with others and what they commit to themselves for the sake of God. Contracts here refer to religious contracts (ʿuqūd al-dīn), which are what a person obligates themselves to, such as buying, selling, leasing, marriage, divorce, and other matters that do not deviate from Islamic law. They also include what a person commits to themselves for the sake of God in terms of acts of obedience, such as Hajj, fasting, and vows.