Narrated to me Abu al-Rabi' and Abu Kamil, both said: Hammad narrated to us, from Ayyub. (Another chain:) And Qutaybah narrated to us, from Hammad, from Ayyub, from Nafi', from Ibn 'Umar, who said: The Messenger of Allah, peace and blessings be upon him, said: "Respond to the invitation when you are invited."