But Fadak remained the symbol of the lost justice according to the Ahl al-Bayt (A.S.); for al-Zamakhshari says in his Rabi' al-Abrar,
"Harun al-Rashid kept pressing Mousa ibn Ja'fer (A.S.) to take Fadak back, and he kept refusing. When he insisted that he should, he said, `I shall not take it back except in its boundaries.' He asked him, `And what are its boundaries?' He said, `The first is Aden;' al-Rashid's face changed colour and he asked him, `And what is the second boundary?' He said, `Samarkand;' now his face started shaking in outrage. He asked him, `And what is the third boundary?' He said, `Africa;' and the caliph's face now turned black in anger, yet he asked him, `And what is the fourth boundary?' He said, `The ocean, and whatever is beyond the Caspian Sea and Armenia.' Harun al-Rashid then said, `There is nothing left for us; so, come and take my throne as well!' The Imam (A.S.) said, `I had told you before that if I defined its boundaries, you would refuse to give it back to me.'"
From this dialogue between Imam Mousa ibn Ja'fer (A.S.) and Harun al-Rashid, we can comprehend the vast dimension of the significance of Fadak to Ahl al-Bayt (A.S.), and that it did not represent simply a piece of land and a few palm trees but a big missionary objective whose significance was linked to the significance of the Message itself in its connotation and depth.
source : www.abna.ir