The purpose of waqf, as stated by Imam Ahmad bin Hanbal in the definition of endowment according to Shariah, is to draw closer to Allah SWT.
The act of waqf is also included in the concept of ongoing charity (sadaqah jariyah), which promises continuous rewards as mentioned in a Hadith of Prophet Muhammad SAW narrated by Muslim, which means:
"When a person dies, his deeds come to an end except for three things: ongoing charity, beneficial knowledge, and a righteous child who prays for him."