Musnad Ahmad 1013:25

Sa'id ibn Mansur narrated to us, Ya'qub ibn 'Abd al-Rahman narrated to us, from Abu Hazim, from Sahl ibn Sa'd, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "I and the guardian of the orphan are like these two in Paradise," and he pointed with his index and middle fingers, and he separated them slightly.