Final answer:
Iago says the lines 'I follow him [Othello] to serve my turn upon him. ...In following him, I follow but myself.' in Shakespeare's Othello.
Step-by-step explanation:
The lines 'I follow him [Othello] to serve my turn upon him. ...In following him, I follow but myself.' are spoken by Iago in Shakespeare's play Othello. In these lines, Iago reveals his true motives and manipulative nature. He follows Othello in order to serve his own selfish interests and seeks to use Othello for his own advantage.