«خَلِّيهْ عَلَى هَوَاهْ لَمَّا يِجِي دِيلُهْ عَلَى قَفَاهْ»

At its plainest, the saying tells the listener to let a certain person go on as he pleases. The opening words describe leaving him to his own inclinations, so the advice concerns standing aside and allowing his will to run unchecked, without saying what kind of person he is.

The closing image, a tail arriving at the nape, sets a limit whose sense stays open and is not fixed to any single outcome. It may point to a moment when the person meets some unwelcome result, or to a moment so odd it may never come. Both readings remain possible.

Suited to remarks about someone being left to follow his own wishes, whoever that person may be. Because the tail-and-nape ending carries no settled sense, use the saying without presenting it as a firm forecast of how that person will fare.