When the Messenger of Allah ﷺ entered the prayer, he would raise his hands fully extended.
حدثنا مسدد حدثنا يحيى عن ابن أبي ذئب عن سعيد بن سمعان
كان رسول الله ﷺ إذا دخل في الصلاة رفع يديه مدا
[Its isnad is hasan] Tirmidhi narrated it in the chapters on prayer, in the chapter on spreading the fingers during the takbir, hadith no. 240, from the hadith of Ibn Abu Dhib, through this same chain, and he said, hasan.