In the Raamaayan, Hanumaan is said to have rescued Shani, that is, the planet Saturn, from the clutches of Raavan. This happened during the burning of the Lanka episode in the epic Raamaayan. In gratitude, Shani promised Hanumaan that those who prayed to him (Hanumaan) would be rescued from the painful effects of Saturn, which in Hindu astrology, is said to produce malefic effects on one's life when one is afflicted "negatively" with Saturn. (read Shani and Raavan)

Another version of the encounter between Lord Hanuman and Shani Bhagavaan is that once Shani climbed on to Lord Hanuman's shoulder, implying that he (Hanumaan) was coming under the effects of the influence of Shani. At this, Hanuman assumed a large size, and Shani was caught painfully between Hanuman's shoulders and the ceiling of the room they were in. As the pain was unbearable, Shani requested Hanuman to release him, promising that if a person prayed to Hanumaan, he (Shani) would moderate the malefic effects of his influence on that person; following this, Hanuman released Shani.

One more version of the story behind why Lord Shani stays away from those who remember the Lord Ram's name. Once Hanumaan Jee was sitting silently absorbed in deep meditation of Shree Raam. Shani passed by and he felt to tease Hanumaan so he started teasing him by pulling his tail, and pinching him. Hanumaan warned him to go away as he is his Guru's (Lord Sun) son so he respects him. When Shani did not hear, then Hanuman started to give him a good thrash. In the end, Shani pleaded to leave him and Hanumaan took a promise from him that Shani will never ever go near a devotee who is meditating on Lord Raam.

There is a spiritual interpretation of the relation between Hanumaan and Shani. The former is said to be a symbol of selflessness, while the latter is symbolic of ego and pride. Thus, to counter the Karm borne out of selfish action, one must be humble like Hanumaan. This is particularly true for those who are said to be experiencing the evil effects of Saadhe Saatee - a period of about seven and half years when Shani (Saturn) is supposed to afflict the three signs - one in which the Moon is placed in the natal chart of a person and the two house around it.

Why People Give Mustard Oil on Saturday in the Name of Shani?

When Shree Raam was building the bridge from Raameshwaram to Lankaa to cross the ocean for His army, Hanuman had the responsibility of looking after the security of bridge lest the enemy damage it. One day Hanumaan was sitting under a tree and offering prayer to God Raam, that Shani Dev came there and said to Hanuman - "I am the most powerful god Shani dev. I heard you are also so powerful, so I want to test your might with me. Open your eyes and fight with me."

In response to Shani Dev's challenge, Hanumaan opened his eyes and said - "Presently I am meditating upon my Lord. I request you not to disturb me in my prayers and leave me alone." But Shani Dev was adamant on picking a fight. At the same time, Hanumaan stretched out his tail and started binding it around Shani Dev. Slowly he tightened the coiled tail and Shani Dev felt the tight grip around him. He tried to free himself but he could not. Hanumaan moved his tail up and down hitting him against the stone of the bridge. Shani Dev started bleeding.

When the pain was unbearable, Shani requested to him - "Release me. I will never do a similar mistake again." Hanumaan replied - "If you promise me that you shall never afflict Raam's devotees then only I will let you go." In the great pain Shani Dev had to promise to Hanumaan, "I will do as you say, I will never interfere in the destiny of those devoted to you and Ram. Please let me go." Hanumaan loosened his tail's grip and Shani got freed.