بُلُوغُ الْمَرَامِ
Bulugh al-Maram 359
The Book of Prayer
وَلِلْخَمْسَةِ عَنْهَا : { مَنْ حَافَظَ عَلَى أَرْبَعٍ قَبْلَ اَلظُّهْرِ وَأَرْبَعٍ بَعْدَهَا حَرَّمَهُ اَللَّهُ عَلَى اَلنَّارِ } [1]
And in the narration of al-Khamsah, by her [Umm Habibah (RA)]: "Whoever prays regularly four Rak'at before and four Rak'at after the Zuhr prayer, Allah will forbid for him (from entering) the Hellfire."
Sunnah.com reference: Book 2, Hadith 262