Sahih Al Bukhari – Book of Characteristics Of Prayer

Volumn 001, Book 012, Hadith Number 725. 
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Narated By Jabir bin Samura RA: Sa'd RA said, "I used to pray with them a prayer similar to that of Allah's Apostle PBUH (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 RA said to Sa'd RA "This was what we thought about you." 

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