Musnad Ahmad 27:27

Ishaq ibn Yusuf narrated to us, from Sufyan, from Ibn ‘Ajlan, from al-Qa‘qa‘ ibn Hakim, who said: ‘Abd al-‘Aziz ibn Marwan wrote to Ibn ‘Umar, “Submit your need to me.” Ibn ‘Umar wrote back to him: “The Messenger of Allah, peace and blessings of Allah be upon him, used to say: ‘The upper hand is better than the lower hand, and begin with those whom you support.’ I will not ask you for anything, nor will I reject a provision that Allah has provided for me through you.”