Does a triple divorce take effect on the wife if the husband says, "My wife is thrice divorced if she said this to your wife," intending whether she said it with the aim of causing a separation between them?

If your pronouncement of divorce was: "My wife is divorced by three [irrevocable divorces] if she said this to your wife," and you meant by that statement that she said it with the intention of causing a separation between your friend and his wife, then it later becomes clear that your wife did not intend that, the divorce does not take effect. This is based on the Prophet's (peace be upon him) saying: "Verily, every person will have what he intended." So, if one specifies the general wording of divorce with his intention, that will be accepted from him. And Allah knows best what your intention is.