telepathic link

You forge a telepathic link with one willing creature of your choice within range, psychically linking both of you together permanently. Creatures with Intelligence scores of 3 or less aren't affected by this spell.

Once the link is created he targets can communicate telepathically through the bond whether or not they have a common language. The communication is possible over any distance, though it can't extend to other planes of existence. Only a wish spell can sever the bond once it is created.