Musnad Ahmad 21:20

Husayn ibn Ali narrated to us, from Za'idah, from Yazid ibn Abi Ziyad, from Abdullah ibn al-Harith, from al-Abbas, who said: I came to the Messenger of Allah, may Allah bless him and grant him peace, and said: "O Messenger of Allah, teach me something that I may supplicate with." He said: "Ask Allah for pardon and well-being (al-afiyah)." He said: Then I came to him another time and said: "O Messenger of Allah, teach me something that I may supplicate with." He said: "O Abbas, O uncle of the Messenger of Allah, may Allah bless him and grant him peace, ask Allah for well-being (al-afiyah) in this world and the Hereafter."