Sheikh Muhammad al-Manî`î, professor at Umm al-Qurâ University
The Prophet (peace be upon him) said "You should pay the laborer his wages before his sweat dries." [Sunan Ibn Mâjah (2443)]
This hadîth is authentic. Numerous scholars, including al-Albanî, have graded it so. It is also quite clear and self-explanatory. Workers are to be paid on time.
If a person is hired to do a job, he should be paid immediately. However, if there is a contractual agreement that wages are to be paid weekly or monthly, then this is what must be done.
Our Prophet (peace be upon him) said: "The procrastination of the rich is an oppression that entitles him to be spoken against and to be punishment.”
He also said: “Whoever oppressed another for a handspan measure of land will have a collar of seven lands placed around his neck on the Day of Judgment.”
The rights of a person are highly regarded in Islam. In his Last Sermon during the Pilgrimage, the Prophet (peace be upon him) said: “Your blood, your money, and your kin are sacred and cannot be taken by force, just as this day in this month in this land is sacred."
Source: Islam Today