Rasul Allah SAW described a man in the Day of Judgment who comes with good quality and quantity of worship that he did for 70 years. The man then asks Allah to judge him not based on Allah's mercy but based on his good deeds. Allah SWT out of His wisdom then gives him that option and tells the angels to take just one of the so many blessings, which is the blessing of the eyesight, and then put it on one side of the balance against all his good deeds. This just one blessing of eyesight then outweighs all the 70 years of excellent worship. With this hadith hopefully we begin to understand the aayat, wa qaleelum min ‘ibaadiyash shakoor, "and few of my servants are thankful".