Hadith 1072

Abu Hurairah (May Allah be pleased with him)reported: The Messenger of Allah (PBUH) said, "If they knew the merits of Salat after nightfall ('Isha') and the morning (Fajr) Salat, they would come to them even if they had to crawl to do so."

[Al-Bukhari and Muslim]

This is part of a long Hadith which has already been mentioned. See Hadith No. 1033.