Vidi et alium eiusdem ordinis virum beatum, valde longaeva aetate provectum, Donodem nomine, Frisonem natione, qui praedicatione sedula, tantum in sua Frisonum gente profecit ut eam a ferocitate sua plurimum mitigaret. ab antiquissimo enim tempore in consuetudinem immanissimam haec habebant Frisones: ut occiso homine unius cognationis ab altera, occisum corpus non sepeliebatur a suis, sed suspensum in loculo servabatur et desiccabatur in domo, quousque ex cognatione contraria in vindictam occisi, plures vel saltem unum adversa cognatio, pro morte vicaria, trucidaret; et tunc primum mortuum suum sepulturae debitae cum magna solemnitate tradebat. hunc crudelissimum et inauditum morem dictus frater in illa gente removit, et ad mitiorem statum crebra exhortatione promovit.
(Thomas of Cantimpré, Bonum Universale de Apibus 2.1.15)
I have also seen another blessed man of the same order*, advanced to an extremely high age, called Dodo, a Frisian. He had served his Frisian people through dedicated preaching so that he greatly pacified them from their savageness. From very ancient times the Frisians had cherished a most horrible custom that when a man of one kindred had been killed by another kindred, the corpse of the killed man was not buried by his kinsmen but was preserved, suspended in a corner, and dehydrated in the house until the hostile kindred slaughtered many or at least one of the opposing kindred in revenge by way of compensatory death. And only then their victim was given a proper burial with great ceremony. The aforementioned brother removed from his people this most cruel and unheard of custom and advanced them to a gentler condition of life by frequent exhortation.
*of Premonstratensians
(tr. Rolf Bremmer, with his note)
Crambe Repetita 