When a traveller leaves his original place, he can shorten his Salat (prayer) Sahih al-Bukhari 1090
Arabic hadith text
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتِالصَّلاَةُ أَوَّلُ مَا فُرِضَتْ رَكْعَتَيْنِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ، وَأُتِمَّتْ صَلاَةُ الْحَضَرِ.قَالَ الزُّهْرِيُّ فَقُلْتُ لِعُرْوَةَ مَا بَالُ عَائِشَةَ تُتِمُّ قَالَ تَأَوَّلَتْ مَا تَأَوَّلَ عُثْمَانُ
Translation
Narrated `Aisha
"When the prayers were first enjoined they were of two rak`at each. Later the prayer in a journey was kept as it was but the prayers for non-travelers were completed." Az-Zuhri said, "I asked `Urwa what made Aisha pray the full prayers (in journey)." He replied, "She did the same as `Uthman did."