Ali from his father from Amr ibn Uthman from Muhammad ibn Udhafir from Abu Abdillah عليه السلام, peace be upon him, who said:
Imam al-Sadiq عليه السلام said: “When the horses move about in turmoil with swords clashing, two takbirs suffice him (for prayer). This is another form of shortening (taqsir).”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 332