Explanation:

When some Muslim clerics (Maulanas) complained about givining protection to Dara Shikoh by Guru Har Rai Ji, to Aurangzeb, the latter summoned Guru Har Rai to Delhi. The Guru refused to go and instead sent his elder son Ram Rai to represent Him at the Mughal Court. Ram Rai worked miracles there and left them dazzled. Then, the clerics and the Islamic scholars questioned Ram Rai about a verse in the Granth Sahib, which they felt offended Muslims.
In order to please Aurangzeb, Ram Rai replied that the text had been corrupted by ignorant persons and His Majesty?s religion as well as his defamed. What Guru Nanak Dev actually says is: Mitti beimaan kee, i.e., the ashes of the dishonest persons (not of the Muslims) falls into the potter?s clod. The faces of the dishonest person shall be blackened in both worlds. The Emperor and all the courtiers were pleased with the reply. When news of the moral weakness of twisting the Hymn of Guru Nanak Dev by Ram Rai reached Guru Har Rai, He disowned his son and ordered him not to show Him his face, as he no more remained his son as he had altered a Hymn of Guru Nanak Dev.