Sahih al-Bukhari 432
Sahih al-Bukhari · Book 8: Prayers (Salat) · The dislikeness of offering As-Salat (the prayers) in grave-yards
Narrated Ibn `Umar:
حَدَّثَنَا مُسَدَّدٌ ، قَالَ حَدَّثَنَا يَحْيَى ، عَنْ عُبَيْدِ اللَّهِ ، قَالَ أَخْبَرَنِي نَافِعٌ ، عَنِ ابْنِ عُمَرَ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " اجْعَلُوا فِي بُيُوتِكُمْ مِنْ صَلاَتِكُمْ، وَلاَ تَتَّخِذُوهَا قُبُورًا " .
The Prophet (ﷺ) had said, "Offer some of your prayers (Nawafil) at home, and do not take your houses as graves."