Jonah sets out upon his journey; not to Nineveh, however, but to flee to Tarshish, i.e., Tartessus, a Phoenician port in Spain (see at Gen 10:4 and Isa 23:1), “from the face of Jehovah,” i.e., away from the presence of the Lord, out of the land of Israel, where Jehovah dwelt in the temple, and manifested His presence (cf. Gen 4:16); not to hide himself from the omnipresent God, but to withdraw from the service of Jehovah, the God-King of Israel.
(Note: Marck has already correctly observed, that “this must not be understood as flight from the being and knowledge of God, lest we should attribute to the great prophet gross ignorance of the omnipresence and omniscience of God; but as departure from the land of Canaan, the gracious seat of God, outside which he thought, that possibly, at any rate at that time, the gift and office of a prophet would not be conferred upon him.”)
The motive for this flight was not fear of the difficulty of carrying out the command of God, but, as Jonah himself says in Jon 4:2, anxiety lest the compassion of God should spare the sinful city in the event of its repenting. He had no wish to co-operate in this; and that not merely because “he knew, by inspiration of the Holy Spirit, that the repentance of the Gentiles would be the ruin of the Jews, and, as a lover of his country, was actuated not so much by envy of the salvation of Nineveh, as by unwillingness that his own people should perish,” as Jerome supposes, but also because he really grudged salvation to the Gentiles, and feared lest their conversion to the living God should infringe upon the privileges of Israel above the Gentile world, and put an end to its election as the nation of God.
(Note: Luther has already deduced this, the only true reason, from Jon 4:1-11, in his Commentary on the Prophet Jonah: “Because Jonah was sorry that God was so kind, he would rather not preach, yea, would rather die, than that the grace of God, which was to be the peculiar privilege of the people of Israel, should be communicated to the Gentiles also, who had neither the word of God, nor the laws of Moses, nor the worship of God, nor prophets, nor anything else, but rather strove against God, and His word, and His people.” But in order to guard against a false estimate of the prophet, on account of these “carnal, Jewish thoughts of God,” Luther directs attention to the fact that “the apostles also held at first the carnal opinion that the kingdom of Christ was to be an outward one; and even afterwards, when they understood that it was to be a spiritual one, they thought that it was to embrace only the Jews, and therefore 'preached the gospel to the Jews only' (Acts 8), until God enlightened them by a vision from heaven to Peter (Acts 10), and by the public calling of Paul and Barnabas (Acts 13), and by wonders and signs; and it was at last resolved by a general council (Acts 15), that God would also show mercy to the Gentiles, and that He was the God of the Gentiles also. For it was very hard for the Jews to believe that there were any other people outside Israel who helped to form the people of God, because the sayings of the Scripture stop there and speak of Israel and Abraham's seed; and the word of God, the worship of God, the laws and the holy prophets, were with them alone.”)
He therefore betook himself to Yāphō, i.e., Joppa, the port on the Mediterranean Sea (vid., comm. on Jos 19:46), and there found a ship which was going to Tarshish; and having paid the sekhârâh, the hire of the ship, i.e., the fare for the passage, embarked “to go with them (i.e., the sailors) to Tarshish.”