Musannaf Ibn Abi Shayba 13:1069

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Abu ‘Umays, from Yazid ibn Ja’daba, from ‘Ubayd ibn al-Sabbaq, from Zaynab al-Thaqafiyya, the wife of ‘Abdullah, that the Prophet, peace and blessings of Allah be upon him, gave her a harvest of fifty wasqs of dates and twenty wasqs of barley. ‘Asim ibn ‘Adi said to her, “If you wish, I will pay them to you here in Medina, and you pay them in Khaybar.” She said, “Until I ask the Commander of the Faithful, ‘Umar.” So she asked him, and he said, “And what about the guarantee?”