He performed the bowing before reaching the row, so the Prophet ﷺ said to him, "May Allah increase you in eagerness, but do not do it again."
حدثنا يحيى حدثنا أشعث عن زياد الأعلم عن الحسن
أنه ركع دون الصف فقال له النبي ﷺ زادك الله حرصا ولا تعد
Its isnad is sahih. Ashath is Ibn Abdul-Malik Hamrani, the jurist, and he is trustworthy, his hadith appears in Bukhari. Ziyad al-Alam is Ibn Hassan, and he is trustworthy, his hadith also appears in Bukhari.The hadith was narrated by Bukhari 2/267, no. 783 Fath, Abu Dawud 1/180, no. 683, and Nasai 2/118, in the Book of Prayer, ruku, without mentioning the row.