The people from Jerusalem would have readily related that statement to the Temple in Jerusalem, for the fire of the temple was burning twenty-four hours a day. It was a beacon that could be seen from miles away, in all directions. The Temple was the ultimate light on the hill, and the people in the temple made it much more than just a building: the priests were there keeping fires burning, and they had to have righteous people there performing the ordinances and sacrifices. However, in the 3 Nephi version, Jesus explicitly said to all of the multitude—men, women, and children—“I give unto you.” In other words, He challenged all of them to “be the light of this people.” He was saying that, as a temple community, they will be a light on a hill as was and is the temple.
In verse 15, Jesus asked, “Do men light a candle,” that is in Greek a lamp (luchnos), which refers to a little clay lamp. Does a person light their lamp and put it under a bushel (a modius)?No. When you light a lamp, you put it on—not a candlestick because they did not have candles—but on a luchnia. In Exodus (in the Greek Septuagint), the word luchnia exclusively means the menorah of the temple. Thus, Jesus instructs each of us to bring our lamp and add it to the light of the menorah, which was the light within the temple. Your light, then, would add to the light upon the hill of the temple. It would shine so that everyone in the House of Israel would see.
What is a modius? A “bushel” is a very rough approximation for what the Greek indicated. In the traditional Greek dictionary (LS), it is defined “as a dry measure of about two gallons.” That word, of Latin origin, was used almost exclusively with regard to the Egyptian god Serapis. Serapis was a male god in Egypt that was the companion of Isis. He was an agricultural god; they sacrificed to Serapis and he would make their crops grow. He always wore a modius, a measuring container on his head, as his cap or crown. Jesus may have been teaching that you should not put your light under one of those pagan gods that the Gentiles worship, because they were to understand instead that He was the light they should be holding up.
Book of Mormon Central, “What Makes 3 Nephi the Holy of Holies of the Book of Mormon? (3 Nephi 14:13–14),” KnoWhy 206, (October 11, 2016).