Even if you had evidence of it, such an agreement would be a mere nudum pactum, binding neither upon himself nor his heirs.

Martyrium autem quatuor fratrum nostrorum in illa ciuitate Thana fuit per istum modum; dum praedicti fratres fuerant in Ormes, fecerunt pactum cum vna naui vt nauigarent vsque Polumbrum, et violentèr deportati sunt vsque Thanam vbi sunt 15.