Van der Vaart has admitted that he is unhappy at Real Madrid.
Jol told Welt am Sonntag: “I am keeping tabs on Rafael’s progress at Bernabeu.
“And I feel if Rafael thinks he has to leave Madrid to return to Bundesliga, his destination can only be HSV.
“We are really in touch with him and know how he feels, simply because of his close friendship to Joris Mathijsen.
“I am really feeling sorry for Rafael as a player. If he had stayed on with us, he could have become a club legend.
“Like Uwe Seeler or Kevin Keegan. There was no doubt about his importance for the club when he was at HSV.”