Musnad Ahmad 26:666

Waki’ narrated to us, al-A’mash narrated to us, from Shaqiq, from ‘Abdullah; and ‘Abd al-Rahman narrated to us, from Sufyan, from Mansur and al-A’mash, from Abu Wa’il, from ‘Abdullah, who said: Paradise. And Waki’ said, from Shaqiq, from ‘Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Paradise is closer to one of you than the strap of his sandal, and the Fire is likewise."