This quote is taken from an article written by Rabbi Dovid Heber titled “MEAT AND DAIRY-A KOSHER CONSUMER’S HANDBOOK”:
“Kosher homes typically have two sets cookeware, dishes, and cutlery – one for meat and one for dairy. This is because it is Biblically prohibited to eat something that contains both milk and meat that were cooked together. Because of this concern, the Rabbis decreed that one who wants to eat a dairy product must wait six hours after eating meat.”
He cites to The Torah, which states three times – “Do not cook a young animal in its mother’s milk.” He explains, from these, the Gemara derives three prohibitions – one may not eat milk and meat together, one may not cook them together, and one may not derive benefit from such cooked mixtures. If they were mixed without heat (e.g. a sandwich containing slices of cold salami and cheese) the mixture is Rabbinically prohibited to eat. See Shulchan Aruch YD87:1. Also, he explains the Gemara Chulin (105a) states that Mar Ukva waited until the “next meal” before eating dairy. The overwhelming majority of Rabbis in the 11th to 15 Centuries were of the opinion that this means one must wait six hours. The Law based on the Torah, as stated in Shulchan Aruch YD 89:1, is that one must wait a full six hours.
However, the angels who visited Abraham did not observe this rule. Of course the Law of Moses was instituted generations later. However, if this rule were of eternal significance it would be expected that the angels would refuse to violate the standard, although mankind would not be asked to do so until centuries later.
Here is how that event transpired: “Abraham ran unto the heard and fetched a calf, tender and good, and gave it unto a young man, and he hastened to dress it. And he took butter, and milk, and the calf which he had dressed, and set before them. And he stood by them under the tree and they did eat.” Gen. 7:35 in the Restoration Scriptures. Later, having finished eating the non-kosher meal, “the angels rose up from there” and went on. Id. paragraph 37.
As Joseph Smith explained, “It is not to be understood that the law of Moses will be established again with all its rites and variety of ceremonies; this has never been spoken of by the Prophets; but those things which existed prior to Moses’ day, namely sacrifice, will be continued.” This is because the Law of Moses came to an end through the Messiah. See Mosiah 8:1; 3 Ne. 7:2
I see no harm if someone wants to observe the Law of Moses. But if they do so, they should understand the purpose of that Law was to foreshadow and testify of the Messiah. Of His sacrifice that offered Himself for sin. Of His taking upon Himself the chastisement of our peace. That He was wounded for our transgressions, he was bruised for our iniquities, and with his stripes we are healed. Isa. 19:2
But there is no need to observe a Law which the angels disregarded when visiting Abraham. There is, on the other hand, every need to recognize and accept the Lord’s anointed, the Messiah, to whom the Law of Moses pointed.