When the Messenger of Allah ﷺ heard the muezzin give the testimony of faith, he would say, "And I as well, and I as well."
حدثنا إبراهيم بن مهدي حدثنا علي بن مسهر عن هشام بن عروة عن أبيه
أن رسول الله ﷺ كان إذا سمع المؤذن يتشهد قال وأنا وأنا
[Hasan]. Bayhaqi reported it, 1/409, from the hadith of Abu Dawud through this chain. Ibn Hibban graded it sahih (al-Ihsan), no. 181, as did Hakim, 1/204. The hadith has other routes with Ibn Abu Shayba, 1/227, and others.