When the Messenger of Allah ﷺ said the takbir to begin the prayer, he would spread out his fingers.
حدثنا قتيبة وأبو سعيد الأشج قالا حدثنا يحيى بن اليمان عن ابن أبي ذئب عن سعيد بن سمعان
كان رسول الله ﷺ إذا كبر للصلاة نشر أصابعه
No references are available.
Its isnad is daif. Ibn Khuzayma also reported it, no. 4581, from the hadith of Abu Saeed Ashaj with the same wording, and Ibn Hibban graded it sahih, no. 446, as did Dhahabi in Talkhis Mustadrak, 1/235. Yahya bin Yaman was truthful and devout in worship, but he erred frequently and his memory had deteriorated (Taqrib, 7679). His hadith in Sahih Muslim is sahih, and the meaning of this hadith has supporting evidence.