[ULPIANUS libro octauo ad Sabinum. ] §28.7.4.prSi qui ita sint instituti: 'si socii una bonorum meorum permanserint usque ad annos sedecim, heredes sunto', inutilem esse institutionem secundum uerborum significationem Marcellus ait: Iulianus autem, quoniam et ante aditam hereditatem iniri societas potest quasi rei futurae, ualere institutionem, quod est uerum.
[ULPIAN, in the eighth book on Sabinus.] If any persons should be instituted in this way: "if they remain partners together in my estate for sixteen years, let them be heirs," Marcellus says that according to the literal meaning of the words the institution is invalid; but Julian says that, since a partnership can be entered into even before the inheritance is accepted, as if concerning a future thing, the institution is valid, which is true.
§28.7.4.1Idem Iulianus scribit eum, qui ita heres institutus est, si seruum hereditarium non alienauerit, cauentem coheredi implere condicionem: ceterum si solus heres scriptus sit, sub impossibili condicione heredem institutum uideri: quae sententia uera est.
The same Julian writes that he who has been instituted heir under the condition "if he does not alienate a slave of the inheritance" fulfills the condition by providing a guarantee to his co-heir; but if he has been written as sole heir, he is considered to have been instituted under an impossible condition; which opinion is true.