Shani Yantra - The word shani also denotes the seventh day or Saturday in most Indian languages. The word shani(शनि) comes from shani dev vedic mantra Shanaye Kramati Sa: (शनये क्रमति सः) , the one who moves slowly, as Saturn takes about 30 years to revolve around the Sun. Shani is also known as Shanaishchar (शनैश्चर), Shanaishchara, Shani Bhagavan, Shaneesvara, Saneesvara, shani yantra, Shaneesvaran, Shani Deva.
Shani Dev Vedic Mantra. ऊँ शन्नो देवीरभिष्टडआपो भवन्तुपीतये। Om Shanno devīrabhistdaapo bhavantupītaye. Shani is a deva and son of Surya (the Hindu sun god) and his wife Chhaya (Shadow goddess) and hence also known as Chayyaputra. He is the elder brother of Yama, the Hindu god of death, who in some scriptures corresponds to the deliverance of justice. Interestingly, Surya's two sons Shani and Yama judge. Shani gives us the results of one's deeds through one's life through appropriate punishments and rewards; Yama grants the results of one's deeds after death.