Rasulullah salla Llahu ‘alayhi wa sallam would divide the khums into six portions… two portions for his relatives
كان رسول الله يقسم الخمس على ستة … و سهمان لأقاربه
Rasulullah salla Llahu ‘alayhi wa sallam would divide the khums into six portions … two portions for his relatives.
I did not locate it in any hadith compilation. The Shia have referenced it to Tafsir al Naysaburi, published on the margins of Tafsir al Tabari.
This demonstrates their bankruptcy. They are incapable of citing a hadith with our isnad which meets our standards of authenticity and which we have classified as sahih.
 Tafsir al Naysaburi vol. 10 pg. 4.