(110) باب يُطَوِّلُ فِي الرَّكْعَةِ الأُولَى
Narrated `Abdullah bin Abi Qatada:
My father said, "The Prophet (ﷺ) used to prolong the first rak`a of the Zuhr prayer and shorten the second one and used to do the same in the Fajr prayer."
Reference: Sahih al-Bukhari 779
In-book reference: Book 10, Hadith 174
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 12, Hadith 746