In the gospel of Mark (1:2) it says..
“As it is written in the prophet ISAIAH, ‘See, I am sending my messenger ahead of you,who will prepare your way….”
now if you searched in the whole book of Isaiah, you will never find this verse .. but you will find it in the book of Malachi (3:1)
if the gospel of Mark is inspired by God, how can it have such a mistake ?!