The mentioned Hadith was related by Imam Ahmad in his Musnad (Hadith compilation), Al-Tabarany in "Al-Mu`jam Al-Kabir" and Ibn Hibban in his Sahih (authentic) Book of Hadith with a good Isnad (chain of narration) on the authority of Abu Umamah Al-Bahily (may Allah be pleased with him) that the Prophet (peace be upon him) said: The knots of Islam will be undone one by one. Each time one knot is undone, people will cling to the one next to it. The first of them to be undone is ruling and the last is Salah.