Shortening the Prayers (At-Taqseer)

Bukhari :: Book 2 :: Volume 20 :: Hadith 195

Narrated Anas bin Malik :

offered four Rakat of Zuhr prayer with the Prophet (p.b.u.h) at Medina and two Rakat at Dhul-Hulaifa. (i.e. shortened the 'Asr prayer).