Musnad Ahmad 1273:17

Yunus ibn Muhammad narrated to us, Hammad—meaning ibn Zayd—narrated to us, from ‘Asim, from Abu Salih, from Umm Habibah bint Abi Sufyan, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever prays twelve rak'ahs in a day, other than the obligatory prayer, Allah will build for him—or he said: a house will be built for him—in Paradise."