Musnad Ahmad 30:3622

'Abd al-Samad narrated to us, 'Abd al-Rahman narrated to us, from his father, from Abu Salih, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "A man passed by a thorny branch, so he removed it from the road. Allah thanked him for it and admitted him into Paradise."