Sunan Ibn Majah, Volume 1, Book 4, Hadith 797 (DarusSalam) ⓘ

It was narrated that Abu Hurairah said: "The Messenger of Allah said: 'The most burdensome prayers for the hypocrites are the 'Isha' prayer and the Fajr prayer. If only they knew what (reward) there is in them, they would come to them even if they had to crawl.'"

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، أَنْبَأَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ إِنَّ أَثْقَلَ الصَّلاَةِ عَلَى الْمُنَافِقِينَ صَلاَةُ الْعِشَاءِ وَصَلاَةُ الْفَجْرِ وَلَوْ يَعْلَمُونَ مَا فِيهِمَا لأَتَوْهُمَا وَلَوْ حَبْوًا ‏" ‏ ‏.‏