JMNT(i)
29 Now with the progressive assembling (collecting; convening) of the crowds into a thick mass (or: a throng), He began to go on to say, "This generation is, and continues being, a worthless (unsound; miserable; wicked; depraved; evil; malicious; disadvantaged; unprofitable; painfully bad; toil-bringing) generation. It is constantly seeking a sign (= insisting on a proof of My claims) – and yet no sign will proceed being given to it except Jonah's sign (or: the sign of Jonah; the sign which is Jonah; the sign pertaining to or in relation to Jonah).
30 "You see, just and correspondingly as Jonah came to be a sign to (for; among) the Ninevites, in the same way the Son of the Man (the Son of mankind; = Adam's son; = the Human Being; = the eschatological Messianic figure) will also proceed being [a sign] to (for; among) this generation.