Musnad Ahmad 28:352

'Abd al-Rahman narrated to us, Sufyan narrated to us, from Abu Ishaq, from Wahb ibn Jabir, from 'Abdullah ibn 'Amr, may Allah be pleased with them both, who said: I heard the Prophet, peace and blessings of Allah be upon him, saying: "It is sufficient sin for a person that he neglects those whom he provides for."