Musnad Ahmad 30:3159

Narrated to us Abd al-Rahman, from Zuhayr, from al-Ala’, from his father, from Abu Hurayrah, from the Prophet, may God bless him and grant him peace, who said: "While a man was walking on a road, he found a thorny branch. He said: 'I will surely remove this, perhaps God Almighty will forgive me for it.' So he removed it, and God forgave him for it, and admitted him into Paradise."