The Prophet ﷺ assigned the grandmother a sixth as her share of inheritance when there is no mother below her in lineage.
أن النبي ﷺ جعل للجدة السدس إذا لم تكن دونها أم.
It was narrated by Abu Dawud (2895) and Nasai in Al-Kubra (6338), both from the hadith of Ubaydullah bin Abdullah, Abu Muneeb Al-Ataki, from Ibn Burayda, from his father, and so he mentioned it. Ubaydullah bin Abdullah Al-Ataki is a subject of disagreement. Bukhari said, "He has objectionable narrations." Aqeeli said, "He is not corroborated in this." But Abu Hatim said, "He is sound." He objected to Bukhari's including him in his book Ad-Duafa, saying, "He should be moved." Ibn Main and Nasai both deemed him trustworthy, and Ibn Adi mentioned him in Al-Kamil, saying, "In my view, there is no harm in him." Ibn Sakan mentioned this hadith in his Sahih, as noted in Talkhis (3/83).The conclusion regarding him is that his hadith is hasan, so long as there is no objectionable element or contradiction in what he narrates, and what has preceded may serve as corroborating support for him.