The Messenger of Allah ﷺ said, "Maintain proper balance in prostration, and let none of you spread out his forearms the way a dog stretches out."
قال رسول الله ﷺ: اعتدلوا في السجود، ولا يبسط أحدكم ذراعيه انبساط الكلب.
Bukhari related it in adhan (822), and Muslim in prayer (493), both of them through Muhammad bin Jafar, from Shuba, who said, I heard Qatada, from Anas, and he related it.