Mark 1:2
The citation introduced as written in Isaiah the prophet actually combines Exodus 23:20 (I will send my messenger ahead of you), Malachi 3:1 (who will prepare your way), and Isaiah 40:3 (a voice calling in the wilderness). The combination is deliberate: all three texts speak of a messenger who prepares the way for the divine arrival. Mark attributes the whole citation to Isaiah because Isaiah 40 provides the interpretive lens — the new exodus motif in which God returns to his people after the exile through a way prepared in the desert. The messenger-before-the-Lord pattern frames John's entire ministry: he is not the main event but the preparation for it.