In Mahābhārata, Anuśāsana Parva we see that when Yudhisthira asked Bhishma to say about Lord Shiva , Bhisma expressed his inability to do so but when Yudhisthira asked to glorify Vishnu ji then Bhisma didn't hesitateto glorify Shri Hari Vishnu. Bhisma said he can't glorify Lord Shiva only Krishna...