Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) said: The Prophet (peace and blessings be upon him) came to us while we were seven men, three Arabs and four of our mawali (freed slaves and clients). The Prophet (peace and blessings be upon him) came out from one of his apartments to us and sat with us, and he (peace and blessings be upon him) said: "What has made you sit here?" We said: "We are waiting for the prayer." He (peace and blessings be upon him) began to scratch the ground with his fingers, then kept his head lowered for a while, then raised his head towards us and said: "Do you know what your Lord, the Mighty and Majestic, says?" We said: "Allah and His Messenger know best." He (peace and blessings be upon him) said: "He says: Whoever prays the prayers at their times and upholds their limits will have a covenant that I will admit him to Paradise. And whoever does not pray the prayers at their times and does not uphold their limits will have no covenant with Me; if I wish I will admit him to the Fire, and if I wish I will admit him to Paradise."
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16364