Musnad Ahmad 1153:1382

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, from 'Amarah ibn 'Umayr, from his paternal aunt, from 'Aishah, that the Prophet, peace and blessings of Allah be upon him, said: "A man's child is from his earnings, and from the purest of his earnings."