Proverb: don't be too sure about the future — no one knows what will happen (literally, mention next year and the ogres laugh).
来年のことを言うと鬼が笑うけれど、今から準備を始めた方が安心だ。
They say you can't be sure about next year, but it's still safer to start preparing now.
彼は来年に昇進すると断言したが、周りは『来年のことを言うと鬼が笑うよ』と笑った。
He insisted he'd be promoted next year, but others laughed, saying 'nobody knows the future.'