Who was the first prophet quoted in the gospel of Mark?

Mark quotes Isaiah in chapter 1 verses 2 - 3:

1.) The beginning of the good news about Jesus the Messiah, the Son of God,

2.) as it is written in Isaiah the prophet:

"I will send my messenger ahead of you,

who will prepare your way"

3.)"a voice of one calling in the wilderness,

'Prepare the way for the Lord,

make straight paths for him.''