Al-Kāfi

Hadith 1269
prostration
3ـ جَمَاعَةٌ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنْ فَضَالَةَ بْنِ أَيُّوبَ عَنِ الْحُسَيْنِ بْنِ عُثْمَانَ عَنْ سَمَاعَةَ عَنْ أَبِي بَصِيرٍ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ لاَ تُقْعِ بَيْنَ السَّجْدَتَيْنِ إِقْعَاءً.
3. A group has narrated from Ahmad ibn Muhammad ibn ‘Isa from al-Husayn ibn Sa‘id from Fadalah ibn Ayyub from al-Husayn ibn ‘Uthman from Sama‘ah from abu Basir who has said the following: “Abu ‘Abd Allah (a.s.), has said, ‘You must not sit, between the two sajdah, placing your hips on your heels.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī