It was near the time of Tabernacles, a feast observed annually by the Jews.
His brothers said, "Why don't you leave here and go up to the Feast so your disciples can get a good look at the works you do?
No one who intends to be publicly known does everything behind the scenes. If you're serious about what you are doing, come out in the open and show the world."
His brothers were pushing him like this because they didn't believe in him either.