Most people who understand at least a bit of Indian astrology, fear Shani Dev. However, it is partially because of their little knowledge of the Hindu mythology. While it is true that when Shani Dev decides to look at somebody, the person might get destroyed, but the God himself is not a cruel deity.
He only punishes people for their mistakes and does not forgive easily. People worship him in various ways to get his blessings and save themselves from his anger at their unintended mistakes. Life becomes a complete blessing when Shani Dev decides to bless his devotees.
One of the ways of pleasing Shani Dev is by worshipping his wives. It is said that he had eight wives named Dhwajini, Dhamini, Kankali, Kalahpriya, Kantaki, Turangi, Mahishi and Aja. One should chant the names of his wives in order to please Shani Dev. It is highly beneficial if their names are chanted on a Saturday. The belief that Shani Dev's sight is considered to be malicious came from the story associated with an incident with his wife Dhamini.
Shani Dev is the son of Surya Dev and his wife Chhaya. He is dark in complexion and rides a chariot made of iron and a vulture is his mount. Shani Dev was a staunch devotee of Lord Krishna since his childhood days. He often used to sit for long hours meditating on Lord Krishna. His love for Krishna remained the same when he grew up. Upon being an adult, he was married to the daughter of Chitrarath. His wife, named Dhamini was a woman with divine powers. Besides being beautiful, she was also very intelligent.
Once while pondering over several thoughts, a desire caught Dhamini's heart that she should be the mother of a boy child. With this desire in her heart, she approached Shani Dev, who was meditating on Lord Krishna at that time and did not want to be disturbed. She tried waking him up from meditation, but all her efforts went futile.
Annoyed by Shani Dev' behaviour, she cursed him that since he paid no heed and did not look at her when she wanted to speak to him, whoever he looks at henceforth, shall get destroyed. Since he ignored her frequent requests to listen to her, his sight would always bring negative effects for people. A person would have to face problems if Shani Dev ever looked at them. Probably that is why it is said that Shani Dev is not bad, but his sight on a person might prove malicious.
As Shani Dev opened his eyes, after completing a round of meditation, he saw that his wife was annoyed and tried to apologise to her. Though she could understand it and regretted for having given the curse, she possessed no such powers which could nullify the effects of the curse. All she could do was nothing but console Shani Dev. However, to make sure that his devotees are saved, he decided never to look at them and keep his head down.