Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

Tahdhīb al-Aḥkām|Volume 3|Book 1|Chapter 3

Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

وَ عَنْهُ عَنِ اَلنَّضْرِ عَنْ عَاصِمٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ عَنْ أَبِي جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ قَالَ:« إِذَا أَدْرَكْتَ اَلتَّكْبِيرَ قَبْلَ أَنْ يَرْكَعَ اَلْإِمَامُ فَقَدْ أَدْرَكْتَ اَلصَّلاَةَ»

And from him, from al-Nadr, from Asim, from Muhammad ibn Muslim, from Abu Ja’far , peace be upon him, who said: Imam al-Baqir said: “If you catch the takbir before the imam (of prayer) bows into rukuh, then you have caught the prayer.”

Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 47
Shaykh Baqir al-Behbudi
Ṣaḥīḥ al-Tahdhīb

Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

Volume 3, Book 1, Chapter 3

Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

Hadith #63