(12) باب تَأْخِيرِ الظُّهْرِ إِلَى الْعَصْرِ
Narrated Ibn `Abbas:
"The Prophet (ﷺ) prayed eight rak`at for the Zuhr and `Asr, and seven for the Maghrib and `Isha prayers in Medina." Aiyub said, "Perhaps those were rainy nights." Anas said, "May be."
Reference: Sahih al-Bukhari 543
In-book reference: Book 9, Hadith 20
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 10, Hadith 518