The hadiths tell us about the deeds that will be weighty on the Day of Judgment and they will not only be the source of salvation but also the reason for prominence for that person. This actually refers to the salient points of the Islamic system.
The Messenger of Islamic is reported to have said:
Nothing will heavier than good behavior on the scales and a person with good behavior will be equal in rank with those with most fasting and those with more prayers.” (1)
In another hadith the Messenger of Islam spoke about the Oneness of God and his own prophethood:
“The scale side from which these two things are removed will be light and the sides that have them will be heavy.” (2)
There is another Hadith from Imam Baqir or Imam Sadiq in which wither of them has said:
“There will be nothing heavier on the weighing scale than the praise (Salawat) of Mohammad and his progeny. The entire deeds of some people will be put on one side but it will still be light then the Durood (Praise) for Mohammad and his progeny will be kept with them and their side will become heavy.” (3)
Some hadiths say:
“Some people say that “Alhamdulillahi wa subhanallahi wallahu Akbar” and “La Illaha Illalllah “will fill the scale of deeds on the Day of Judgment. (4)
What we learn here is that some times some deeds that seem very ordinary and small have such a great important in the eyes of God that they fill the scales of deeds. This is because of their great value in Islam.
The reality of Oneness of God, of Hamd, rosary, and the spiritual attachment to Mohammad and his progeny and the good behavior are such deeds. You have also read that one date fruit spent with pious intentions in the way of God weighs down the scale of deeds though the scale cover the entire earth and the heavens.
Some hadith have also told us that mankind will also be put on the scales and weighed. There is a hadith in which the Messenger is reported to have said:
“On the Judgment Day a very fat person will come whose weight will not be equal to even that of a mosquito’s. (5)
This is because these people are empty from inside though their deeds in this world, their thoughts and personalities may seem beautiful.