Who was the first to establish an endowment (waqf) in Islam after the Battle of Khaybar?

The first to establish an endowment (waqf) in Islam was the Prophet Muhammad, peace and blessings be upon him. This occurred after the Battle of Uhud, in the third year of the Hijra, when he endowed the lands of Mukhayriq, which Mukhayriq had bequeathed to the Prophet, peace and blessings be upon him. Then came the endowment of Umar ibn al-Khattab, may Allah be pleased with him, in the seventh year of the Hijra, after the conquest of Khaybar.