Final Dispositor of the Chain (Taslīm al-Tadbīr)
Definition
In Masha'allah's horary and electional doctrine, the final dispositor is the planet at the end of a chain of handed-over disposition — the one to whom the management of a matter finally arrives. Planets commit their disposition to one another by reception and by pushing, and the planet that receives it and commits it to no one else becomes the significator of the outcome: if its nature works toward effecting the matter, the matter is brought about; if toward prohibiting, it is denied. The Latin tradition named this terminus the ultimus recipiens dispositionem, the last receiver of the disposition.
In Tradition
The Arabic-Persian horary tradition reads a question not from one significator in isolation but from where the disposition finally comes to rest. A planet hands over the affair either by reception proper — being in another's domicile or exaltation and joined to it — or by pushing its disposition to a planet it merely contacts. The planet that takes the disposition and passes it no further, especially if strong in its place, carries the verdict, and its condition and nature decide the outcome.
In Practice
Trace the disposition through the chart rather than stopping at the first significator. Begin with the planet that signifies the matter, then follow where it commits its disposition: to the planet that receives it into its own domicile or exaltation, or to a planet it merely pushes to by aspect or conjunction. Keep following each hand-over until you reach a planet that takes the disposition and commits it to no one further — the terminus of the chain. Judge that planet as the significator of the outcome: weigh its essential dignity and its strength of placement, whether it is free of the Sun's beams and the malefics, and above all its nature toward the affair. A terminus inclined to effecting brings the matter about; one inclined to prohibiting denies it. Distinguish true reception, where the receiving planet welcomes the visitor into its own dignity, from a merely pushed disposition, which the sources warn is the weaker, less stable transfer.
Historical Origin
The doctrine is set out in Masha'allah ibn Athari's On Reception (preface and Ch 1) and his On Hidden Things, where the planet 'joined to no one' that has not committed its disposition onward, and is strong in its place, is named the significator. Benjamin N. Dykes's Works of Sahl & Masha'allah (2008) preserves both treatises and identifies this terminus as the final dispositor. The precept is carried forward into the Sahl, Abu Ma'shar, and Bonatti horary traditions.