Ibn ‘Abbas said, “God has prescribed the prayer by the tongue of your Prophet (ﷺ) as four <i>rak'as</i> when resident, two when travelling, and one when danger is present.” Muslim transmitted it.

وَعَنِ ابْنِ عَبَّاسٍ قَالَ: فَرَضَ اللَّهُ الصَّلَاةَ عَلَى لِسَانِ نَبِيِّكُمْ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي الْحَضَرِ أَرْبَعًا وَفِي السَّفَرِ رَكْعَتَيْنِ وَفِي الْخَوْف رَكْعَة. رَوَاهُ مُسلم