I never saw the Messenger of Allah ﷺ raise his hands while supplicating, neither on his pulpit nor anywhere else. Rather, I saw him do like this, and he pointed with his index finger while joining the middle finger with the thumb.
حدثنا مسدد حدثنا بشر يعني ابن المفضل حدثنا عبد الرحمن يعني ابن إسحق عن عبد الرحمن بن معاوية عن ابن أبي ذباب
ما رأيت رسول الله ﷺ شاهرا يديه قط يدعو على منبره ولا على غيره ولكن رأيته يقول هكذا وأشار بالسبابة وعقد الوسطى بالإبهام
[Its chain of transmission is daif] Bayhaqi narrated it, 3/210, from the hadith of Abu Dawud, through him. Ahmad narrated it, 5/337, from the hadith of Abdul-Rahman bin Ishaq, through him, and Ibn Khuzayma graded it sahih, no. 1450.Abdul-Rahman bin Muawiya bin Huwayrith was deemed daif by the majority, and the rest of the chain is hasan.