بُلُوغُ الْمَرَامِ
Bulugh al-Maram 419
The Book of Prayer
وَعَنْ أَبِي بَكْرَةَ - رضى الله عنه - أَنَّهُ اِنْتَهَى إِلَى اَلنَّبِيِّ - صلى الله عليه وسلم -وَهُوَ رَاكِعٌ, فَرَكَعَ قَبْلَ أَنْ يَصِلَ إِلَى اَلصَّفِّ, فَقَالَ لَهُ اَلنَّبِيُّ - صلى الله عليه وسلم -{ زَادَكَ اَللَّهُ حِرْصًا وَلَا تَعُدْ } رَوَاهُ اَلْبُخَارِيُّ . [1] .
Narrated Abu Bakrah (RA): He reached the Prophet (ﷺ) while he was bowing, so he (Abu Bakrah) bowed before reaching the row. He mentioned that to the Prophet (ﷺ) and the Prophet (ﷺ) said to him, "May Allah increase your eagerness! But do not repeat." [Reported by al-Bukhari].
Sunnah.com reference: Book 2, Hadith 324