Musnad Ahmad 30:1251

Abu Bakr al-Hanafi narrated to us, al-Dahhak bin Uthman narrated to us, from Sa’id al-Maqburi, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, when one of you is in the mosque, the devil comes and nudges him, just as a man nudges his riding beast. If he settles down for him, he puts him in a chokehold or bridles him." Abu Hurairah said: "You see that; as for the one in a chokehold, you see him leaning like this, not remembering Allah. And as for the one bridled, he is opening his mouth, not remembering Allah."