Sahih Al Bukhari Hadith Number 1101

Narrated Hafs bin `Asim: Ibn `Umar went on a journey and said, “I accompanied the Prophet (peace be upon him) and he did not offer optional prayers during the journey, and Allah says: ‘Verily! In Allah’s Messenger (peace be upon him) you have a good example to follow.’ ” (33.21)

18  Shortening the Prayers (At-Taqseer)
Hadith number 1101
Volume no 2
Chapter: 11 ( Whoever did not offer the Nawafil before and after the (compulsory) Salat during a journey)