Musannaf Ibn Abi Shayba 28:928

Muhammad ibn Fudayl narrated to us, from ‘Ata’ ibn al-Sa’ib, from his father, from ‘Abdullah ibn ‘Amr, who said: A man came to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, I pledge allegiance to you for Jihad." The Prophet, may Allah bless him and grant him peace, said to him: "Do you have two parents?" He said: "Yes." He said: "Go, and strive in them (by serving them) a good striving."