Planet Saturn, one of the nine planets, Navagraha.
Sani is worshiped with oil. Once Sani went to Hanuman to measure his strength with him. Hanuman felt disturbed and tied Sani with his tail. Sani tried to free himself when Hanuman hit him several times against a stone until he was bleeding. Sani asked for oil for his wounds. Hanuman gave it to him. He smeared his body and was healed.
Read about Sani here