To add to the previous discussion,

Many proverbs are often expressed (in any language) by archaic and old-fashioned language (including this specific way of using short forms), so the modern and customary forms of grammar may look a bit altered in them.

The explanation is very practical: Language changes, but proverbs are SET wordings, and word order and older forms are not likely to change in them. So many Russian proverbs are not easy to grasp at once, as they may contain vocabulary and grammar not often used today.