Description of the Prayer from Its Beginning to Its End
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 46
وَ سَأَلَ رَجُلٌ أَمِيرَ اَلْمُؤْمِنِينَ عَلَيْهِ اَلسَّلاَمُ فَقَالَ: يَا اِبْنَ عَمِّ خَيْرِ خَلْقِ اَللَّهِ عَزَّ وَ جَلَّ مَا مَعْنَى مَدِّ عُنُقِكَ فِي اَلرُّكُوعِ فَقَالَ «تَأْوِيلُهُ آمَنْتُ بِاللَّهِ وَ لَوْ ضُرِبَتْ عُنُقِي.
A man asked The Commander of the Faithful Imam Ali ibn Abi Talib عليه السلام saying: "O’ son of the cousin of the best of Allah’s سبحانه وتعالى creation, what is the significance of extending your neck during ruku' (bowing in prayer)?" Imam Ali عليه السلام responded, "It symbolizes 'I have faith in Allah سبحانه وتعالى, even if my neck is struck.'"
- Ṣaḥīḥ al-Faqīh