Shani believed that he can sit on the head of all living beings on earth for 7.5 years (Sade Sati) and create problems for the beings in Kali Yuga. Hanuman is Chiranjeevi and still roams on earth. Shani one day approached Hanuman told him that he does not care if he is god, as per the rule of Kaliyuga, he had sit on Hanuman’s head for 7.5 years.
Hanuman then told Shani that he resides in the feet of Lord Ram and time has no effect on him. Shani too would not have any effect on him.
Shani told Hanuman that he cannot change the rules of Kali Yuga.
Then, Hanuman asked where he wanted to stay in his body. Shani told Hanuman that he stays only on the head of the living being and he makes them do unwanted things that will cause problems in their life.
Without waiting much, Shani entered the head of Hanuman.
Hanuman felt something was itching on his head.
Hanuman immediately took a small boulder and placed it on his head.
Shani got crushed under the weight of the boulder.
Shani asked why Hanuman he was carrying the boulder on head.
He told Shani that as he was bound by the laws of Kali Yuga just like him he kept boulders on his head whenever he felt itching.
Saying this hanuman now lifted a small hill and kept it on his head.
Shani was pressed down even harder and Shani asked Hanuman to get rid of the boulder and hill.
Hanuman said he was bound by his nature and now he lifted a mountain and placed it on top of the hill. Shani was crushed further and soon realized that he would die inside Hanuman’s head.
Shani asked Hanuman to taken down the mountain and save him. He told Hanuman that he will never visit him again.
But Hanuman lifted a fourth mountain and placed it on top of his head.
Shani was not able to move and words hardly came out of his mouth. Shani somehow convinced Hanuman that he will not visit Hanuman and his true devotees.
Hanuman took down the two mountains, a hill and boulder and rescued Shani.
Shani without looking back ran away from Hanuman.
From that day onwards, Shani stopped bothering Hanuman and his true devotees.