How is waqf established?

An endowment (waqf) is established through an explicit pronouncement such as "I have endowed," "I have dedicated," or "I have made it a sabil (endowment)," these being terms well-established by custom and Islamic law. Alternatively, it can be established through an implicit expression (kinayah) accompanied by the intention (niyyah), such as "I have given as charity," "I have made it forbidden," or "I have made it perpetual." These implicit terms are not explicit because they share other meanings, and an endowment is not established by them alone. However, an endowment is established by them if another word indicating endowment is added to them (such as "a dedicated charity"), or if they are described with the characteristics of an endowment (such as saying: "it is not to be sold, nor gifted, nor inherited"), or if the intention to endow is present. The intention makes it an endowment in its inner reality, though not outwardly, unless acknowledged.