According to the famous verses at Surat Al Kahf, 60-74:
And [mention] when Moses said to his servant, "I will not cease [traveling] until I reach the junction of the two seas or continue for a long period."
Until Moses met with Khidr, where they later went on a ship:
So they set out, until when they had embarked on the ship, al-Khidh r tore it open. [Moses] said, "Have you torn it open to drown its people? You have certainly done a grave thing."
So they set out, until when they met a boy, al-Khidhr killed him.
Where did Moses follow al-Khidr? (or where did they met the boy?)