I went on an expedition with the Messenger of Allah ﷺ, and I was present with him at the conquest. He stayed eighteen days in Mecca and prayed only two rak'ahs (at each time of prayer). And he said: You who live in the town must pray four; we are travellers.
غَزَوْتُ مَعَ رَسُولِ اللَّهِ ﷺ وَشَهِدْتُ مَعَهُ الْفَتْحَ فَأَقَامَ بِمَكَّةَ ثَمَانِيَ عَشْرَةَ لَيْلَةً لاَ يُصَلِّي إِلاَّ رَكْعَتَيْنِ وَيَقُولُ يَا أَهْلَ الْبَلَدِ صَلُّوا أَرْبَعًا فَإِنَّا قَوْمٌ سَفْرٌ