Shani is one of the Navagrahas which are the nine primary celestial beings in Hindu astrology. Shani is embodied in the planet Saturn. Shani is the Lord of Saturday; the word Shani also denotes the seventh day or Saturday in many Indian languages.

The legend that depicts the influence of the worship of SHANI is narrated whenever a worship or offering is made to the deity.The legend pertains to a king. The king invited merchants from far and wide and proclaimed that the king himself would purchase all unsold goods. The merchants were happy. Once a blacksmith brought an iron image of Saturn for sale, which ultimately was purchased by the king, who installed that in his palace with reverence. Other gods became unhappy at this action of the king. At night, the king saw a woman going out of the house. On the king's enquiry, he learnt that,it was Lakshmi. She said that she could not stay in the place where Saturn is present.

After sometime a male image went out and was told to be Bhaivabh (Prosperity).Similarly all other gods Dharma (Religion), Dheriye (Patience), Kshama (Pardon)and all others went out. When the last Satya (Truth) was going out, the king protested and said that because of faith in Satya, he did not object to the others from going out. Feeling the sentiments of the king, Satya stopped. All other deities were waiting outside for Satya, but when he did not come out Dharma (religion) said that he could not remain without Satya; so he returned. Similarly all others followed and all gods and attributes came back inside the palace.They told the king that only because of his devotion to the Satya (truth); they all had to return and that such a king could never be unhappy. Due to the devotion to Satya, (truth), Lakshmi (wealth) and Shani (Saturn) came to live together,to benefit the devotees.

Another Legend 
A different version of the legend is also popular. It is as follows:Once there was a dispute between the nine planets as to who is superior among them. When they could not decide, they all went to Indra the king of gods, who was also as puzzled. So he advised that they should go to the just and benevolent king Vikramaditya. King Vikramaditya, after great thought got seven seats spread out, the first of gold and the last of iron. He then requested the deities to take their seats.Shani (Saturn) knew that his seat was iron seat viz. the last and as much, he was recognized as inferior to all. Therefore he cursed Vikramaditya and said "Surya stays on one Zodiac for one month, the moon for two days, Mangal (Mars) for one and a half month, Brihaspati (Jupiter) for thirteen months, Budha (Mercury) andShukra (Venus) for one month each and Rahu, Ketu for eighteen months only; but I (Saturn) stay at one Zodiac for thirty months: I have made many gods suffer because of my power and influence. Due to my influence Rama and Lakshmana were exiled and Ravana suffered a defeat and his dynasty destroyed, so a king, you beware of my wrath". The king said, "whatever be my luck, I shall face it."After some time a merchant selling beautiful horses came to Ujjain, the capital of Vikramaditya. The courtiers praised the horses and requested the king to visit. When the king came, he took a fancy for the particular horse and to try the same,he got on the saddle. The horse took to its heels and flew into the forest, with none to accompany or follow the king. In the forest where no one knew him, desperate with hunger and thirst, he sought refuge in the house of a rich merchant. The merchant judging him as a good person allowed him (king) to stay in his house.At night, Vikramaditya saw that a pearl necklace hung on a peg, was being swallowed by the peg. The next day when the merchant found the necklace missing, he reported the matter to the kotwal who had king Vikramaditya's hands and legs amputated. The king was then left helpless. An oil crusher took pity on him and employed him to sit on the crusher and tend to the bull. While sitting, handicapped and helpless, Vikramaditya used to sing. One day, the princess of the kingdom heard the song and was charmed by it. She sent her maidens to find out who the singer was and made up her mind to marry him. Her parents tried their best to dissuade her but she did not agree. She was married to the handicapped person (Vikramaditya). At night Shani appeared in his dream and said that all his sufferings were because he (King) had decided that Saturn was inferior. The king begged for forgiveness, worshiped and sought his blessings. The king (Vikramaditya) then narrated his story of woe to his bride. Saturn blessed the couple so that they would lead a happy married life. His limbs were restored. The rich merchant invited them to his house and to the surprise of everyone present the lost necklace oozed out from the peg. The merchant felt ashamed and asked to be pardoned and offered his daughter in marriage to Vikramaditya. Then Vikramaditya returned to Ujjain with his two brides amidst a rousing reception.

This is planet Saturn, whose influence is dreaded, and who is at best respected for his powers as a bringer of harsh karmic lessons, at worst feared and shunned. There is much more to Shani than meets the eye. The planet has many ambiguities in its nature and influence. Saturn, Lord Shani, is cold, earthy, masculine and dry, but - yet another ambiguity, the son of the fiery, hot, energetic Sun. Shani's mother is Chaya or shadow, who in the myth sneaked in to unite with the Sun, much to his dismay. The Sun is therefore no friend of Lord Shani. The planet brings karmic lessons to the individual human soul in a patient but unmistakeable way. Sani's karmic retribution is always just .. and accurately balanced. But the planet is uncompromising in its action. There are different propitiations for planets - but Sani is the one planet unlikeliest to be placated or fooled by insincere, rushed measures to ward off his ill affects. This is not his nature.Sani traditionally governs age, longevity, restriction, discipline, elders, ancestors, asceticism, restriction. Lord Sani is not a planet that always inflicts harm.It also signifies wisdom. The planet at its best brings temperance, moderation, and a quiet, unstated delight in a simple life.It rules hidden wealth, endurance, mental and moral courage.In Vedic astrology, Lord Sani has a special significance in one particular lengthy transit called "Sade Sati". This is when Sani transits the 12th, 1st, and 2nd houses from the house in which your Moon is placed at birth. The period of influence is 7.5 years long- hence the name "Sade Sati" which means seven and a half, and occurs roughly every 30 years. Sade Sati makes everybody particularly nervous - as it seems to threaten untold miseries and calamities. But the period, especially in middle age, all depends on your attitude. Lord Sani occupies everyone's chart, and in each chart also rules two of the twelve houses. Therefore everyone, at some point in their life, comes face to face with his influence.The periods when Sani influences your chart can also turn out to be the best times of your life instead of the guaranteed delay, ageing, holding back- if you seek wisdom and higher understanding.Lord Sani is a respecter of discipline, responsibility, moderation. These are all yogic virtues and vital to an ultimately rewarding life. He represents effort, endeavour, endurance. He is wise, grave, not torn between the demands of the senses.We should learn to live a life full of simple goodness, grow enormously in compassionate wisdom, and understand that even in moments of unhappiness there is great beauty.