A person with a stentorian voice and powerful build is said to be a “bull of Bashan.”
The reference is to the Bible, to Psalms xxii, 12: “Many bulls have compassed me: strong bulls of Bashan have beset me round. They gaped upon me with their mouths, as a ravening and a roaring lion.”
The conquest of Bashan by Moses (Deuteronomy iii, 14), known as the land of giants, was a memorable feat to the Israelites; there are a number of references to it in the Old Testament.
The size and power of the cattle were especially impressive.