Brothers are invited to wear their outdoor work clothes and sisters are invited to wear something modest that they would wear to work in the garden, etc.
“And I said, ‘Now, Wednesday night is–is humble night here at the Tabernacle’. I said, ‘Now, all you brothers, wear your work clothes, your overalls. I’m going to preach in my overalls'”. ~ Rev. William Marrion Branham (50-0200)