Ahmad ibn Muhammad from Muhammad ibn Yahya from Talhah ibn Zayd from Ja'far from his father:
(Imam) Ali عليه السلام said: "Whoever groans during his prayer has indeed spoken."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 354