Waqfs can be as specific as one palm-tree whose produce went to support individuals or to the poor. This document is from 1200 c. H. Madina. Here the word used for waqf is sabl. Other examples also from Gulf could be found in Bahrain, published by Ahmed Mubarak Salem.
Origin: Madina, Saudi Arabia .1200 c. H. / 18 c.
Source: Published in Watha’iq min mantiqat al-Madina al-Munawara, part 1: watha’iq Wadi al-Furra`, vol. 2 (1181-1200 H), published by Fa’iz b. Musa al-Badrani al-Harbi, Madina 2005: p. 1041.