faqih-65Vol. 1, p. 33
الصَّلَاةُ ثَلَاثَةُ أَثْلَاثٍ ثُلُثٌ طَهُورٌ وَ ثُلُثٌ رُكُوعٌ وَ ثُلُثٌ سُجُودٌ[2]
Hadith.66 - Imam Jafar ibn Muhammad Al-Sadiq (as) said: "The prayer consists of three parts: one-third is for purification, one-third is for bowing (ruku), and one-third is for prostration (sujud) "