Narrated by Mu`adh ibn Jabal r.a.:
The Messenger of Allah (Peace Be Upon Him) took hold of my hand and said, “O Mu`adh! By Allah I love you.” Mu’adh responded, “May my father and mother be sacrificed for you, O Messenger of Allah (saw); I love you too.”
Then the Prophet (saw) said, ”I advise you, o Mu’adh to never forget to recite after every prayer:
“Allahumma a`inni ala zikrika, wa shukrika wa husni ibadatika.”
O Allah help me remember you, to be grateful to you and to worship you in the most excellent manner.
{Related by Ahmad, Abu Dawud, an-Nasa’i, Ibn Khuzaimah, Ibn Hibban and al-Hakim}