Ubaydullah bin 'Abdullah bin Umar al-Farooq

'Ubaydullah ibn 'Abdullah ibn 'Umar ibn al-Khattab

His mother was an umm walad, Umm Salim ibn 'Abdullah. His children were Abu Bakr, 'Abdullah, 'Umar, Muhammad, and Umm 'Umar, whose mother was 'Aisha bint 'Abdu'r-Rahman ibn Abi 'Umar, whose mother was 'Aisha bint 'Abdu'r-Rahmaan ibn Abi Bakr; al-Qasim, Abu 'Ubayda, 'Uthman, Abu Salama, Zayd, 'Abdu'r-Rahman, the twins Hamza and Ja'far, Qurayba, and Asma', whose mother was Umm 'Abdullah bint al-Qasim ibn Muhammad ibn Abi Bakr; and isma'il, by an umm walad.

    Khalid ibn Abi Bakr said, "I saw 'Ubaydullah ibn 'Abdullah wearing a white hat with a turban around it whose end hung behind him more than a span."  

'Isa ibn Hafs said, "I saw 'Ubaydullah ibn 'Abdullah wearing two red garments in which he went home after 'Asr and in which he attended 'Isha'."
Muhamad ibn 'Umar said, "According to what they say, 'Ubaydullah ibn 'Abdullah was older than 'Abdullah ibn 'Abdullah. Az-Zuhri related from him."
Khalid ibn Abi Bakr said, "I saw Salim attend 'Ubaydullah ibn 'Abdullah. 'Ubaydullah's grave had a tent over it and water was sprinkled on his grave. He was reliable with a few hadiths."
Source: The Men of Madina Volume II, by Muhammad Ibn Sa'd page 130.