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Possible interpretation: Repair something as soon as it is damaged. That's a small repair job. If not, you will have a much bigger and more expensive repair job later. Do it now and you'll need one stitch. Do it later and you'll need 9 stitches!

Note: stitch (noun) = a link made with thread in sewing; | in time = not late | Why nine and not eight or ten? Perhaps because "nine" rhymes, approximately, with "time".