Manyú, Vedic Sanskrit for "spirit, temper, ardour, passion, anger" is a war god, wielder of thunder and slayer of foes. He is fierce, a queller of the foe and is self-existent. He is beseeched to bring health and wealth. Rig veda 10:83&84 contains Manyu Sukta.Manyu Tapasa is the Drashta of Manyu sukta.
Identification of Manyu with Lord Rudra
Satapatha Brahmana IX-1-1-6 says :
"From Prajapati, when he had become enfeebled, the deities departed. Only one god, Manyu, did not leave him, but continued extended within him. He (Prajapati) wept. The tears which fell from him remained in that 'Manyu'. He became Rudra with a hundred heads, a hundred eyes, and a hundred quivers. Then the other drops which fell from him in unnumbered thousands entered into these worlds.They were called Rudras because they sprang from him when he had wept. This Rudra with a thousand heads, eyes, and quivers, stood with his bow strung,and arrows on the string, causing terror, and demanding food. The gods were afraid of him. They said to Prajapati,:'We are afraid of this being, lest he destroy us.' Prajapati said to them: 'Collect for him food, and with it appease him.' They collected for him this food, the satarudriya." 
- "Hinduism - Gods and Goddess in the Vedas".
- Page 348,Original Sanskrit Texts VOL-IV,By J.Muir,Trubner &co,LONDON,1873