his knowledge of the action of the Prophet (peace and blessings of Allah be upon him). This proves that his action was not fixed [as the only option]. How could it be, when the Prophet (peace and blessings of Allah be upon him) had designated half of Khaybar as a waqf? If it belonged to the conquerors, he would not have been permitted to designate it as a waqf. Abu 'Ubayd (33) said: The reports have reached the level of tawatur (mutawatir) regarding the opening of lands by force through these two rulings: the ruling of the Messenger of Allah (peace and blessings of Allah be upon him) in Khaybar when he divided it—which is what Bilal and his companions advised 'Umar to do regarding the land of al-Sham, and what al-Zubayr advised regarding the land of Egypt—and the ruling of 'Umar in the land of al-Sawad and elsewhere when he designated it as a waqf—which is what 'Ali and Mu'adh advised 'Umar to do (34). The action of the Prophet (peace and blessings of Allah be upon him) does not negate the action of 'Umar, because each one of them followed a decisive verse. Allah the Almighty said: "And know that anything you take as war booty, then for Allah is one-fifth of it" (Quran 8:41). And He said: "And what Allah restored to His Messenger from the people of the towns" (Quran 59:7). Thus, both matters were permissible, and the discretion in that lies with the Imam; whatever he deems appropriate, he carries out. This is the view of al-Thawri and Abu 'Ubayd. Once this is established, the discretion delegated to the Imam is a discretion of (36) benefit, not a discretion of caprice. Therefore, he is bound to carry out what he deems to be in the interest, and he is not permitted to deviate from it, just as in the choice between killing or enslaving, and between ransoming or granting freedom to captives. He does not need to pronounce it as a waqf; rather, leaving it (37) without division is his way of designating it as a waqf, just as dividing it among the conquerors does not require a specific verbal formula (38). This is because it has not been reported that 'Umar or others used a specific formula for the waqf of land. Furthermore, the meaning of designating it as a waqf here is that it remains for all Muslims; its kharaj (land tax) is collected and spent on their interests, and no one is specifically granted ownership of any part of it, and this is achieved simply by leaving it as it is.