It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: If those who stay behind from the Isha and Fajr prayers knew what reward there is in these two prayers, they would surely participate in them even if they had to come crawling on their knees.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 12533
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد حسن فى المتابعات والشواهد الأجل سنان أبى ربيعة الباهلي، وذكره ابن حبان فى الثقات