sweat of one's brow

So anyhow Terry brought the three pints Joe was standing and begob the sight nearly left my eyes when I saw him land out a quid. O, as true as I'm telling you. A goodlooking sovereign. / ― And there's more where that came from, says he. / ― Were you robbing the poorbox, Joe? say I? / ― Sweat of my brow, says Joe. 'Twas the prudent member gave me the wheeze.