[ULPIANUS libro trigesimo secundo ad edictum. ] §21.2.37.prEmptori duplam promitti a uenditore oportet, nisi aliud conuenit: non tamen ut satisdetur, nisi si specialiter id actum proponatur, sed ut repromittatur.
[ULPIAN, On the Edict, Book Thirty-Two] The seller must promise double the price to the buyer, unless it has been agreed otherwise; however, this does not mean that security must be given (unless it is proposed that this was specially agreed upon), but that a bare promise should be made.
§21.2.37.1Quod autem diximus duplam promitti oportere, sic erit accipiendum, ut non ex omni re id accipiamus, sed de his rebus, quae pretiosiores essent, si margarita forte aut ornamenta pretiosa uel uestis Serica uel quid aliud non contemptibile ueneat.
But what we said, that double the price must be promised, is to be understood in such a way that we do not apply this to every transaction, but to those things which are of greater value, as if, for example, pearls or precious ornaments or silk garments or any other thing of non-negligible value is sold.
per edictum autem curulium etiam de seruo cauere uenditor iubetur.
Moreover, by the curule edict, the seller is also commanded to provide a guarantee concerning a slave.
§21.2.37.2Si simplam pro dupla per errorem stipulatus sit emptor, re euicta consecuturum eum ex empto Neratius ait, quanto minus stipulatus sit, si modo omnia facit emptor, quae in stipulatione continentur: quod si non fecit, ex empto id tantum consecuturum, ut ei promittatur quod minus in stipulationem superiorem deductum est.
If the buyer, by mistake, has stipulated for single the value instead of double, Neratius says that, if the thing is evicted, he will obtain by the action on purchase as much as less he has stipulated, provided that the buyer performs all that is contained in the stipulation; but if he has not done so, he will only obtain by the action on purchase that what was less brought into the prior stipulation be promised to him.