Brood of vipers

Jesus called them a brood of vipers because like the first serpent (Ge 3:1 ), they had become subtle or cunning (06175 ערום ‘aruwm) in challenging the word of God, and not only the word, but the Word-Jesus. And like Adam were naked (06174 ערום ‘arowm ) before God.

How did Adam know he was naked ערום? Because he had become cunning ערום. (The same word.)

The Pharisees were always cleverly twisting the scriptures to catch Jesus in a trap. But he knew them. They were naked before him. They were very much like the first serpent.

The same imagery is use when Peter was called Satan. (Mt 16:23 ) Peter had just declared that Jesus was the Messiah, the Son of God. So Jesus tells him about the cross, which is prophesied in scripture. Peter tempts Jesus to avoid the cross suggesting that since he is God, he does not need to die. He challenged the word of God.