A second disputed issue, beyond the question of reference, is the question of which sayings actually represent the words of Jesus. In the pre-critical period, interpreters never raised this question, simply assuming that all the sayings attributed to Jesus were actually spoken by him. The question arose once scholars began to recognize different classes of Son of Man sayings, classes which seemed difficult to reconcile under a single concept. With the advent of the apocalyptic explanation of “Son of Man,” scholars began to see two categories of sayings represented in the Gospels: the apocalyptic sayings, which spoke of the future coming of the Son of Man, and the non-apocalyptic sayings. Other scholars further subdivided the second category into sayings relating to Jesus' earthly ministry in general and those relating specifically to his death and resurrection. Thus developed the three groupings familiar today: sayings concerning the (present) earthly Son of Man, the suffering Son of Man, and the (future) coming Son of Man. Though this threefold grouping is sometimes credited to Bultmann ([1948–53] 1951–55: 1.30), it actually appears in the works of numerous earlier scholars.

For those who accepted the apocalyptic origin of Son of Man, the question became how to relate the apocalyptic sayings to the non-apocalyptic sayings in the Gospels. If the Son of Man was an apocalyptic figure who would come only at the end-time, how could Jesus speak of himself as the Son of Man already in his earthly ministry? As Bousset stated the problem,