Musannaf Ibn Abi Shayba 28:788

Narrated to us Kathir ibn Hisham, from Ja'far ibn Burqan, who said: Narrated to us Thabit ibn al-Hajjaj, who said: It reached me that two men from Banu 'Abd al-Muttalib came to the Prophet, may Allah bless him and grant him peace, asking him for charity. He said: "No, but when you see something from the khums (one-fifth share) with me, then come to me."