Musnad Ahmad 28:309

'Abd al-Razzaq narrated to us, Sufyan informed us, from al-Hasan ibn 'Amr al-Fuqaymi, from Mujahid, from 'Abdullah ibn 'Amr, who said: The Prophet, peace and blessings of Allah be upon him, said: "The one who maintains ties is not the one who reciprocates; rather, the one who maintains ties is the one who, when his kinship is severed, maintains it."