Sahih Muslim, 4212

Mus'ab b. Sa'd reported on the authority of his father. I was ailing. I sent message to Allah's Apostle (ﷺ) saying:Permit me to give away my property as I like. He refused. I (again) said: (Permit me) to give away half. He (again refused). I (again said): Then one-third. He (the Holy Prophet) observed silence after (I had asked permission to give away) one-third. He (the narrater) said: It was then that endowment of one-third became permissible

Rapporté par Mus'ab b. Sa'd, d’après son père رضي الله عنه : J’étais malade. J’ai envoyé un message au Messager d’Allah ﷺ pour lui demander la permission de donner mes biens comme je le souhaitais. Il a refusé. J’ai demandé : « La moitié ? » Il a encore refusé. J’ai dit : « Alors un tiers ? » Le Prophète ﷺ est resté silencieux après que j’ai demandé la permission de donner un tiers. C’est alors que le don d’un tiers est devenu permis