In Islam, the basic rule is that everything is permissible unless it is declared prohibited in the sources (i.e. the Qur’an and the Sunnah). Hence a certain thing or food cannot be considered unlawful as long as there is nothing in the sources to prohibit it.
Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states the following: “There is nothing in the Islamic sources—the Qur’an, Sunnah, `ijma’ (consensus of scholars) and qiyas (analogy)—that makes it haram (unlawful) for a person to drink milk with honey. While discussing haram and halal, it would save us lot of trouble to know that haram is what Allah has declared such. No mortal, no matter how high his status, can declare things as haram based purely on his or her whims and fancies.
Since both milk and honey are halal (lawful) and since there is nothing in the sources that makes consuming either one of them separately or concurrently haram, it shall be considered as halal to do so.
Having said this, however, I must add a word of caution: Should it proven scientifically that mixing honey with milk is in any way harmful to health, we must definitely avoid it.”