Is it true that honey should not be mixed with milk because both are good foods, and good things should not be mixed with their like?

The prohibition has been reported regarding mixing raisins and dates, or semi-ripe dates (busr) and dates, or fresh dates (rutab) and semi-ripe dates (busr), and similar combinations when preparing nabidh (a drink made from dates or grapes) and drinking them. This is because intoxication occurs rapidly due to the mixture before its taste changes, leading the drinker to assume it is not intoxicating while it is. The prohibition here is for a disfavored act (karahat al-tanzih), and it only becomes forbidden (haram (definition)) if it turns intoxicating. As for mixing honey with milk, this does not fall under this prohibition because it is not prepared as nabidh, and there is no Shariah or medical evidence that prohibits mixing good food with other good food. The Prophet, peace and blessings be upon him, used to eat cucumbers with fresh dates (rutab).