Thawāb al-Aʿmāl wa ʿiqāb al-Aʿmāl
Hadith 1041 وَ قَالَ ع قَالَ أَمِیرُ الْمُؤْمِنِینَ ع اللِّوَاطُ مَا دُونَ الدُّبُرِ فَهُوَ لِوَاطٌ وَ الدُّبُرُ هُوَ الْکُفْرُ.
4. It is also narrated that Amirul Momineen (a.s.) said, “If it is done outside anus, it is called sodomy and if it is inside it, it is disbelief.”