It is narrated (as a mawquf narration) from Hazrat Abu Hurairah (may Allah be pleased with him) that any Muslim servant who offers twelve rak‘ahs as voluntary prayers in a day, a house will be built for him in Paradise.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10462
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد حسن