621. hadíth
621 - وَقَالَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «اَلسُّجُودُ عَلَى اَلْأَرْضِ فَرِيضَةٌ وَ عَلَى غَيْرِ اَلْأَرْضِ سُنَّةٌ.
Hadith.621 - Imam Jafar ibn Muhammad Al-Sadiq (as) said: "Prostration (Sujood) on the earth is an obligation, and on anything other than the earth is a recommended practice (sunnah)”.