Chapter on the Prayer Times (Mawaqit)
Tahdhīb al-Aḥkām|Volume 2|Book 1|Chapter 13
عَنْهُ عَنْ حُسَيْنِ بْنِ هَاشِمٍ عَنِ اِبْنِ مُسْكَانَ عَنْ زُرَارَةَ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ:« وَقْتُ اَلظُّهْرِ عَلَى ذِرَاعٍ»
From him, from Husayn ibn Hashim from Ibn Miskan from Zurarah:
Abu Abdillah عليه السلام said: “The time of Dhuhr is when the shadow reaches one arm's span (dhira‘).”
- Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 262
- Ṣaḥīḥ al-Tahdhīb, p. 157