15 If they had been thinking of the country they had left, they would have had opportunity to return.

Read Hebrews 11:15 Using Other Translations

And truly, if they had been mindful of that country from whence they came out, they might have had opportunity to have returned.
If they had been thinking of that land from which they had gone out, they would have had opportunity to return.
If they had longed for the country they came from, they could have gone back.