Matthew 16:4

16:4 A wicked and adulterous generation asks for a sign, but no sign will be given to it except the sign of Jonah.” Then ¹  he left them and went away.

Matthew 12:39

12:39 But he answered them, ²  “An evil and adulterous generation asks for a sign, but no sign will be given to it except the sign of the prophet Jonah.

[16:4]  ¹ tn Here καί (kai) has been translated as “then” to indicate the implied sequence of events within the narrative.

[12:39]  ² tn Grk “But answering, he said to them.” This construction is somewhat redundant in English and has been simplified in the translation.