The Prophet (peace and blessings of Allaah be upon him) said, “The most burdensome prayers for the hypocrites are salaat al-’isha’ and salaat al-fajr, but if they only knew what they contain, they would come even if they had to crawl.

(Reported by Imaam Ahmad, al-Musnad, 2/424; Saheeh al-Jaami’, 133).