Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said: One day the Messenger of Allah (peace and blessings be upon him) took hold of my hand and said: "O Mu'adh! By Allah, I love you." Mu'adh (may Allah be pleased with him) said to him: May my father and mother be ransomed for you, O Messenger of Allah; by Allah, I too love you. He said: "O Mu'adh, I advise you never to leave saying after every prayer: 'Allahumma a'inni 'ala dhikrika wa shukrika wa husni 'ibadatik' (O Allah, help me to remember You, to thank You and to worship You well)."
And Sayyiduna Mu'adh (may Allah be pleased with him) gave this same advice to al-Sunabihi, al-Sunabihi to Abu Abd al-Rahman, and Abu Abd al-Rahman to Uqbah bin Muslim.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17246
Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "The feet of a servant will not move on the Day of Resurrection until he is asked about four things: about his life, in what he spent it; about his youth, how he used it up; about his wealth, from where he earned it and on what he spent it; and about his knowledge, what he did with it."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17247