عَنْ عُبَيْدِ اللَّهِ بْنِ زَحْرٍ أَنَّ أَبَا هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: أَيُّهَا النَّاسُ إِنَّ اللَّهَ فَرَضَ لَكُمْ عَلَى لِسَانِ نَبِيِّكُمْ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ الصَّلَاةَ فِي الْحَضَرِ أَرْبَعًا، وَفِي السَّفَرِ رَكْعَتَيْنِ
Sayyiduna Abu Hurairah (may Allah be pleased with him) says: O people! Allah Almighty has made four rak‘ahs obligatory for prayer during residence and two rak‘ahs for prayer during travel, upon the tongue of your Prophet.