Jonathan Edwards on the need for Christians to be convinced of the continuing obligation of the Sabbath:
If men take it only upon trust, and keep the first day of the week because their parents taught them so, or because they see others do it, they will never be likely to keep it so conscientiously and strictly, as if they had been convinced by seeing for themselves that there are good grounds in the Word of God for their practice. Unless they do see thus for themselves, whenever they are negligent in sanctifying the Sabbath or are guilty of profaning it, their consciences will not have that advantage to smite them for it, as otherwise they would. — And those who have a sincere desire to obey God in all things, will keep the Sabbath more carefully and more cheerfully, if they have seen and been convinced that therein they do what is according to the will and command of God, and what is acceptable to him. [They] will also have a great deal more comfort in the reflection upon their having carefully and painfully kept the Sabbath.
Source and read more: http://www.biblebb.com/files/edwards/sabbath.htm