They well know that prayer at another time than this is more excellent, for Messenger of Allah ﷺ said: The prayer of those who are penitent is observed when your weaned camels feel the heat of the sun.  

أَنَّ الصَّلاَةَ فِي غَيْرِ هَذِهِ السَّاعَةِ أَفْضَلُ إِنَّ رَسُولَ اللَّهِ ﷺ قَالَ صَلاَةُ الأَوَّابِينَ حِينَ تَرْمَضُ الْفِصَالُ  

The prayer of the penitent should be observed when the young weaned camels feel heat of the sun.  

خَرَجَ رَسُولُ اللَّهِ ﷺ عَلَى أَهْلِ قُبَاءٍ وَهُمْ يُصَلُّونَ فَقَالَ صَلاَةُ الأَوَّابِينَ إِذَا رَمِضَتِ الْفِصَالُ