The Messenger of Allah ﷺ, when he prayed, used to spread out his arms away from his sides.
أخبرنا عبدة بن عبد الرحيم المروزي قال أنبأنا ابن شميل هو النضر قال أنبأنا يونس بن أبي إسحق عن أبي إسحق
أن رسول الله ﷺ كان إذا صلى جخى
No references are available.
[Hasan] Bayhaqi transmitted it, 2/115, from the hadith of Nadr bin Shumayl with this chain, and it is also in Sunan al-Kubra, no. 692. Ibn Khuzayma graded it sahih, no. 647. Bayhaqi reported from Abu Zakariya Anbari, who said, "A man does jahh in his prayer when he stretches out his upper arms and holds them away from his body in ruku and sujud." The hadith has corroborating narrations in Abu Dawud, no. 900, and elsewhere.