Sunan Abi Dawud 1250
سنن أبي داود#1250SahihNarrated Umm Habibah:The Prophet (ﷺ) as saying: If anyone prays in a day and a night twelve rak'ahs voluntarily (supererogatory prayer), a house will be built from him in Paradise on account of these (rak'ahs)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim (728)
In-book reference: 5:1