He entered the mosque while the Prophet ﷺ was bowing, so he bowed before reaching the row. The Prophet ﷺ said, "May Allah increase you in eagerness, but do not do it again."
أخبرنا حميد بن مسعدة عن يزيد بن زريع قال حدثنا سعيد عن زياد الأعلم قال حدثنا الحسن أن
أنه دخل المسجد والنبي ﷺ راكع فركع دون الصف فقال النبي ﷺ زادك الله حرصا ولا تعد
Bukhari narrated it in the book of adhan, the chapter titled "When he bows before reaching the row," hadith no. 783, from the hadith of Ziyad Alam, and it is also in Al-Kubra, hadith no. 943. Abu Dawud narrated it, hadith no. 683, from Humayd bin Masada, from him.