The Prophet of Islam (Peace be upon him and his family) has said:
"The Salat is the most important act of worship in the religion. If Allah (SWT) accepts one's Salat, then all other acts of worship will be accepted, and if the Salat is not accepted, then all other acts of worship will not be accepted either."
He (Peace be upon him and his family) has also said:
"One who does not pay importance to the Salat and considers it as something insignificant, is worthy of punishment in the next world."
source : http://www.maaref-foundation.com/
