19 Now Jesus put the two actions together. The walking of the man would be proof (so that you may know) that his sins were forgiven and that God had worked through Jesus (i.e., the Son of Man).
20 The term Son of Man, which is a title in Greek, comes from a pictorial description in Dan 7:13 of one “like a son of man” (i.e., a human being). It is Jesus’ favorite way to refer to himself. Jesus did not reveal the background of the term here, which mixes human and divine imagery as the man in Daniel rides a cloud, something only God does. He just used it. It also could be an idiom in Aramaic meaning either “some person” or “me.” So there is a little ambiguity in its use here, since its origin is not clear at this point. However, the action makes it clear that Jesus used it to refer to himself here.
21 Jesus did not finish his sentence with words but with action, that is, healing the paralytic with an accompanying pronouncement to him directly.

In other versions

But that you may know that the Son of Man has authority on earth to forgive sins”—he said to the paralytic—

But I want you to know that the Son of Man has authority on earth to forgive sins.” So he said to the man,

But so that you may know that the Son of Man has authority on earth to forgive sins”—he told the paralytic—

So I will prove to you that the Son of Man has the authority on earth to forgive sins.” Then Jesus turned to the paralyzed man and said,

But so that you may know that the Son of Man has authority on earth to forgive sins,”—he said to the paralytic—

But that ye may know that the Son of man hath power on earth to forgive sins, (he saith to the sick of the palsy,)

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