Musnad Ahmad 30:3738

'Ali narrated to us, Warqa' informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "While a man was strutting in his two garments, having become pleased with himself, Allah caused the earth to swallow him up. He will continue to sink into it until the Day of Resurrection."