Jābir (may Allah be pleased with him) reported: I heard the Prophet (may Allah’s peace and blessings be upon him) say: "What stands between a man and polytheism and disbelief is the abandonment of the prayers."
The Prophet (may Allah's peace and blessings be upon him) warned against abandoning the obligatory prayers and informed us that what stands between a man and falling into Shirk (polytheism) and disbelief is the abandonment of prayer. Prayer is the second pillar of Islam and is of great significance in this religion. Whoever abandons it out of denial of its obligation has become a disbeliever by consensus among the Muslims, and whoever abandons it altogether out of negligence or lethargy is a disbeliever, a ruling the Companions are reported to have agreed upon unanimously. But if a person abandons it sometimes and performs it at other times, he is subject to this stern warning.