King Shahjahan loved his elder son Dara Shakoh very much. But his younger son Aurangzeb was feeling jealous of it.
One day with the help of a cook he mixed the moustache of a lion in the food of Dara Shakoh.
When Dara Shakoh took that food he fell ill. He was suffering from severe pain in the stomach.
When Shahajahan heard about the suffering of Dara Shakoh he sent for all the experienced physicians working in the royal hospitals. They tried their best but were unable to relieve Dara Shakoh from the severe pain.
At last the physicians said, 'This medicine which can cure Dara Shakoh of this disease lies in the hospital of Guru Har Rai.'
But Shahjahan was hesitant to bring medicine from Guru Har Rai.
He said, 'How the Guru will give the medicine. I have sent my army many times to annihilate them. On the other hand I am a King of India and he is a Darvesh. Will it not be insult on my part to beg medicine from a Darvesh? My dignity does not allow it.'
Pir Hasan Ali and Shekh Abu Gangohi advised him, 'There was no discrimination in the house of Guru Nanak. There are all equal. They love Hindus and Muslims alike. The people of all casts get treatment in his hospital. You should not feel degraded by bringing medicine from their hospital. The hermits keep enmity with none. They are all friends of all.'
Then Shahjahan wrote a letter to Guru Har Rai. This letter he handed over to his trusted courtiers. These courtiers next day reached Kiratpur.
When the Guru heard about their mission, He welcomed them and asked his Sikhs to serve them meals and fruits.
On seeing the grandeur of the Guru, there were much influenced. They were pleased to see the tradition of common kitchen.
The Guru called his physicicians and ordered them to give the courtiers the required medicine. The physicians provided them the medicines and they returned back.
When Dara Shakoh took that medicine he became hale and healthy within a few days. He was very influenced by the benevolence of the Guru. He made up his mind to visit Kiratpur. He reached Kiratpur and thanked the guru for his kindness. He offered many valuable gifts to the Guru.
The Guru blessed him and advised him to always remember God.
He said, 'The Kings must be God fearing.'
Dara Shakoh wrote a poem in the praise of the Guru. He was so influenced by the sermons of the Guru that he stayed for many days with the Guru.
As Dara Shakoh was a very learned man, he studied the Sikh scriptures with great curiosity. He was very impressed on reading the holy hymns of the Gurus.
Later on he became a devout devotee of the Guru.
During the war of succession, when he was fleeing towards Kabul, Guru Har Rai helped him to cross the river Beas.