The Economic System of Islam by Taqiuddin an-Nabhani

One of the kinds of work is the Musaqat, where one person hands over his trees to another person in order to irrigate them and tend to them in return for a defined portion of their fruit. It was called Musaqat (literally meaning irrigation) because it is related to the work of irrigation, where the trees of the people of Hijaz mainly needed irrigation for which they used to draw water from the wells. Musaqat is one of the types of work which Shar’a allows. Muslim has narrated that Abdullah ibn ’Umar (ra) said: “The Prophet (pbuh) of Allah (pbuh) contracted the people of Khaybar over half of what they produce of fruit crops and plants.” Musaqat is allowed in palm trees and vines on a known part of the crops, which are to be given to the worker. This applies only to the trees that have fruit. The trees which either have no fruit (crops) such as the willow, or have fruit not sought after as the pine and cedar, are not allowed for Musaqat, because Musaqat is for a part of the fruit (crops) and these type of trees has no fruit sought after. But those trees whose leaves are sought after such as the mulberry and the rose, Musaqat is allowed in them, because their leaves are equivalent to fruit. This is harvested annually and it is possible to collect it and enter into Musaqat for a part of it, thus invoking the same rule as fruit.