Sayyiduna al-Zubayr bin al-Awwam (may Allah be pleased with him) used to take four shares of the spoils: one share for himself, two shares for his horse, and one for his relatives, the share of his mother Safiyyah (may Allah be pleased with her), on the day of Khaybar. Ibn Uyaynah (may Allah have mercy on him) was wary of mentioning Yahya bin Abbad, whereas the hadith masters (huffaz) narrate it from Yahya bin Abbad.
The Shaykh says: Muhammad bin Bishr narrated it from Hisham bin Urwah, from Yahya bin Abbad, that the Messenger of Allah (peace and blessings be upon him) (did) similarly; and even with Yahya bin Abbad mentioned in it, it is mursal. Sa'id bin Abd al-Rahman and Muhadir bin Muwarri' narrated it with a connected chain from Hisham bin Urwah, from Yahya bin Abbad, from Abdullah bin al-Zubayr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17964
Yahya bin Abbad bin Abdullah bin al-Zubayr narrates from his grandfather (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) allotted four shares to al-Zubayr bin al-Awwam (may Allah be pleased with him) on the day of Khaybar: one share for him, one for his relative, Safiyyah bint Abd al-Muttalib (may Allah be pleased with her), al-Zubayr's mother, and two shares for the horse.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17965