Sahih Bukhari
Characteristics of Prayer
Volume: 001 / Book Number: 012 / Hadith Number: 725
Narrated Jabir bin Samura:
Sa'd said, "I used to pray with them a prayer similar to that of Allah's Apostle (the prayer of Zuhr and 'Asr) reducing nothing from them. I used to prolong the first two Rakat and shorten the last two Rak'at." 'Umar said to Sa'd "This was what we thought about you."