The Ruling on Bequeathing Burial in a Specific Place

Answer: In al Sharah and its marginalia: Ê The relative is, according to the apparent position of the school, more entitled than the executor to perform the prayer over him—because the deceased bequeathed concerning the right of another. The same applies to Ê washing, lowering (into the grave), preparation, and shrouding. Concluded (Í) (affirmed). This is the view of the jurists.
In al-Yāqūtah it is said: the executor is more entitled than anyone else—and this is the view of Aḥmad, Isḥāq, Anas b. Mālik, and Zayd b. Arqam. This is conveyed in Sharḥ al-Azhār.2
I say: Burial in a particular place follows the same difference of opinion.
What appears to me is the view of the school: for in his lifetime, the person himself had the greatest right over his own person; in his death, his relatives have the greater right—unless his relatives are not righteous or not acceptable in their religion, and the deceased has bequeathed one of the aforementioned matters to some righteous person. In that case, the executor takes precedence over the relatives. This is supported by His saying, Exalted is He: “The believing men and the believing women are allies of one another.” [al-Tawbah:71] and the like.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1