Qur'an 18:60

وَإِذْ قَالَ مُوسَىٰ لِفَتَىٰهُ لَآ أَبْرَحُ حَتَّىٰٓ أَبْلُغَ مَجْمَعَ ٱلْبَحْرَيْنِ أَوْ أَمْضِىَ حُقُبًا

“And [mention] when Moses said to his boy [i.e., servant], "I will not cease [traveling] until I reach the junction of the two seas or continue for a long period."”

Al-Kahf 18:60 · Saheeh International