Tafsir of Al-Kahf 18:60

The Story of Musa and Al-Khidr Allah tells:

وإذ قال موسى لفتاه

And (remember) when Musa said to his boy-servant: The reason for Musa's conversation with the boy-servant, Yusha` bin Nun, was that he had been told about one of the servants of Allah at the junction of the two seas, who had knowledge which Musa had not been granted, so he wanted to travel to meet him. So he said to that boy-servant of his:

ﻻ أبرح

I will not give up, meaning, I will keep on traveling,

حتى أبلغ مجمع البحرين

until I reach the junction of the two seas, meaning, the place where the two seas met.

أو أمضي حقبا

or a Huqub passes. meaning, even if I have to travel for a very long time. Ibn Jarir (may Allah have mercy on him) said, "Some of the scholars of the Arabic language said that Huqub means a year in the dialect of (the tribe of) Qays,'' then he narrated that Abdullah bin Amr said, "Huqub means eighty years.'' Mujahid said, "Seventy years.'' Ali bin Abi Talhah reported that Ibn Abbas said that; it means a lifetime. Qatadah and Ibn Zayd said likewise