It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him and his family) said: Every prophet was given a supplication as a gift, and every prophet hastened to have it accepted in this world, but I have postponed my gift for intercession for my Ummah in the Hereafter. While the state of my Ummah will be such that one man will intercede on behalf of large groups of people, and as a result, they will enter Paradise; and one man will intercede on behalf of a tribe, one man on behalf of a group, one man on behalf of three individuals, one man on behalf of two persons, and one man will intercede on behalf of a single individual.

(Second chain) It is stated in this: And a person will intercede for an individual and his family, as a result of which those people will enter Paradise.