Musnad Ahmad 1060:53

Bahz narrated to us, Shu'bah narrated to us, Muhammad ibn 'Uthman ibn 'Abdullah ibn Mawhab and his father 'Uthman ibn 'Abdullah narrated to us, that they both heard Musa ibn Talhah, from Abu Ayyub al-Ansari, that a man said: "O Messenger of Allah, inform me of a deed that will cause me to enter Paradise." The people said: "What is the matter with him? What is the matter with him?" The Messenger of Allah (peace and blessings of Allah be upon him) said: "Let him be, what is the matter with him?" He said: "You worship Allah, not associating anything with Him, you establish the prayer, you give the zakat, and you uphold the ties of kinship. Let it go." He said: "It was as if he was upon his riding beast."