Is a Waqf (endowment) invalid if its initial beneficiary is someone upon whom endowment is prohibited?

Primary text

The endowment is void if it is established initially upon someone upon whom endowment is impermissible, such as the endower himself, his Umm Walad (enslaved concubine), his slave, a church, or an unknown person, provided no alternative permissible beneficiary is stipulated. This invalidity occurs because one of the two essential conditions of the Waqf is violated. Similarly, if the endowed property itself is designated for a purpose or entity that cannot receive endowment, the Waqf is void, similar to bestowing something impermissible to be endowed. If the Waqf is stipulated upon a prohibited beneficiary, such as upon his slave and then upon the poor, its validity is subject to two opinions, depending on whether the transaction can be split ('tafriq al-safqah'). The Hanbali scholar Al-Qadi holds that if the initial prohibited beneficiary is someone whose extinction cannot be considered (like the deceased, the unknown, or churches), the endowment immediately shifts to a permissible beneficiary because assuming validity necessitates ignoring the impermissible recipient. If the prohibited beneficiary is someone whose extinction can be considered (like an Umm Walad or a specific slave), the matter is subject to further division.