Maliks Muwatta Book 15, Hadith Number 26.
Section : Dua (Supplication).
Yahya related to me from Malik from Abu’z-Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, “Every prophet is given a supplication (dua), and I wish to preserve my dua as intercession for my community in the next world.