One of the chief devas.
In the Tevijja Sutta (D.i.244) he is mentioned with Indra, Soma, Varuna, Pajāpati and Brahmā, as being invoked by the brahmins.
He was in the battle of the devas against the Asuras and led a section of the deva host. Indra tells the devas that if, during the struggle, they felt faint-hearted, they should look at the crest of his own banner or at that of Pajāpati, Varuna or īsāna, and their fear would disappear (S.i.219).
In the assembly of the gods, īsāna gets the fourth seat next to Varuna. He is in beauty and longevity equal to Indra (SA.i.262).
īsāna is an older name for Rudra (Siva) (Böthlinck and Roth: Wörterbuch). The conception of him had so far changed by the time of Buddhaghosa that in Buddhaghosa's accounts he is given a seat near Sakka and inferior to his. Perhaps he was one of the thirty-three gods of Tāvatimsa (KS.i.281, n.4).