[Machine] Leaving the call to prayer while traveling is less serious than leaving it while in the city. It was narrated from Asim bin Damarah, from Ali bin Abi Talib, that he said about travelers, "If he wishes, he can make the call to prayer and establish the prayer, and if he wishes, he can establish the prayer without making the call to prayer." Some people falsely attributed this narration to Ibn Umar, and it is a vulgar lie.  

أَنَّ تَرْكَ الْأَذَانِ فِي السَّفَرِ أَخَفُّ مِنْ تَرْكِهِ فِي الْحَضَرِ وَرُوِّينَا عَنْ عَاصِمِ بْنِ ضَمْرَةَ عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ أَنَّهُ قَالَ فِي الْمُسَافِرِ إِنْ شَاءَ أَذَّنَ وَأَقَامَ وَإِنْ شَاءَ أَقَامَ وَبَعْضُ النَّاسِ رَفَعَ حَدِيثَ ابْنِ عُمَرَ وَهُوَ وَهْمٌ فَاحِشٌ