Al-Kāfi

Hadith 1010
worship
6ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ حَمَّادِ بْنِ عِيسَى عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ لِلصَّلاَةِ أَرْبَعَةُ آلاَفِ حَدٍّ. وَفِي رِوَايَةٍ أُخْرَى لِلصَّلاَةِ أَرْبَعَةُ آلاَفِ بَابٍ.
6. Ali ibn Ibrahim has narrated from his father from Hammad ibn ‘Isa who has said the following: “Abu ‘Abd Allah (a.s.), has said, ‘Salah (prayer) has four thousand limits (rules).”’ “In another Hadith it is said that in Salah (prayer) there are four thousand doors (chapters).”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī