The first thing about which a person will be questioned is prayers (Namaz). Did he say his prayers in time? Did he serve (rightly) this pillar of Islam and the Legacy of prayers , or did he recite it to show off. After this people will be questioned about Fasting (siyam), pilgrimage (Haj), Zakat, Khums, the Holy War (Jehad) etc. and then the righful recipients will catch hold of their shirts (and ask for their rights).
Rights of people (Haqqun Naas)
Allah will deal with His servants in two ways, (1) with Justice (Adl), and (2) with mercy (Fazl).
Allah's Justice (Adl): If a person has upon him someone's right (haq), his good deeds (of equal weight or merit) will be handed over to the rightful owner. For example backbiting (gheebat), defaming etc. The good deeds of a person who has backbited or has defamed anyone, will be transferred to the account of the person whom he backbited or defamed, and in turn that person's bad deeds will be transferred to the account of the person who backbited and defamed him.Many traditions (Ahadees) are quoted to support this.
There is a lengthy tradition (Hadees) from Imam Ali