The incident goes as follows -
Once to display the devotion of the gopis to others Krushna pretended that He had intense headache which did not respond to any medicine. Then He pronounced, ‘Krushna’s pain will vanish with the application of mud beneath anyone’s feet. However the one giving the mud beneath his feet will die. Proclaim this and then bring the mud which someone gives.’ No one was prepared to give the mud from under his feet.
On entering Gokul when Uddhav asked this question to the first gopi that he met, she replied, “If the mud under my feet will relieve Krushna’s headache then I am even prepared to go to hell.”
The devotion of the gopis is an illustration of ultimate devotion. Radha among them was like a jewel in the crown.
Futility of misinterpretation of the Radha-Krushna relationship
Radha’s spiritual love (priti) that is devotion unto Krushna has been misinterpreted as love in the Radha-Krushna relationship. Its futility will be realised if one considers Krushna’s age at that time. When Krushna left Gokul; He was only seven years old; thus His relationship with Radha was only during the period when He was three to seven years old.
The sound of the flute means the ‘anahat’ sound. That sound had maddened all the gopis (wives of the cowherds). So one will realise how highly spiritually evolved they were. When leaving Gokul, Krushna gave His flute to Radha and never played it again. Thus He made sure that She constantly got the spiritual experience of Absoluteness (Purnatva) which is superior to anahat sound.
‘Water flows from a higher to a lower level. It is called a stream (dhara). When the letters of the word dhara are reversed the word becomes radha. That stream which flows from below upwards is called radhagati. When it reaches the origin, it gets a spiritual experience of being Radha Herself. Acquisition of this state itself is called “blending into zero” or “sainthood”. In other words Radha and Krushna were one and the same. Krushna had Himself assumed Radha’s form to demonstrate divine love of God to Humanity and to exemplify mirage of his spiritual mode bhaktan-Himself. Therefore, divine devotion and Divine Love merge in LOVE [“prema-priya-bhaktan cha prabhu eka divya-amara-parama-premahanurah”].