Sayyiduna Abu Hurairah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: “No prayer is heavier upon the hypocrites than ‘Isha and Fajr, and if they knew the reward and virtue of these two prayers, they would come to them even if they had to crawl on their knees.”
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1307
(Commentary on Hadiths 1303 to 1307) From all these narrations, the virtue of the Fajr and ‘Isha prayers is understood, and these two prayers are extremely burdensome upon the hypocrites (munafiqun) because these are times of comfort and sleep. The believer (mu’min) attends to perform them with zeal and eagerness, while the hypocrite remains resting and sleeping. It is as if staying behind from these two prayers is a sign of hypocrisy (nifaq). Also, it is evident that the hypocrite is only concerned with worldly desires, whereas the believer gives preference to the Hereafter.