According to research by Gordon Thomasson, John Welch, and Robert Smith, fifty days after Passover on the ancient Israelite calendar was the festival of Pentecost or Shavuot ("Weeks"). Just as Passover marked a time of poverty and bondage, Pentecost exulted in a time of bounty, with offerings of leavened bread baked from the new crop of wheat (see Leviticus 23:17) and of the choicest firstfruits.
About this same time of the year was the day when Moses received the Ten Commandments on Mount Sinai (see Exodus 19:1). Thus, Pentecost probably also celebrated the giving of the law by God to Moses. The connection between Pentecost and the giving of the law is well-documented in the Talmud. A recent opinion of Professor Moshe Weinfeld of the Hebrew University of Jerusalem is that this connection was made very early in Israelite history, as evidenced by Psalms 50 and 81, which he concludes were sung at Pentecost.
With this in mind, the story of Abinadi in Mosiah 11-17 comes to life:
a. Abinadi's re-entry on a festival day would have given him a ready audience.
b. Both of Abinadi's speeches deal with the themes of Pentecost. He reversed the festival's blessings and rejoicing and turned them into curses and predictions of gloom.
c. At precisely the time when Noah's priests would have been hypocritically pledging allegiance to the Ten Commandments (and indeed they professed to teach the law of Moses; see Mosiah 12:27), Abinadi rehearsed to them those very commandments (see Mosiah 12:33). On any other day this might have seemed a strange defense for a man on trial for his life, but not on Pentecost--the day on which the Ten Commandments were on center stage!
d. The connection with Pentecost could hardly have been more graphic than when Abinadi's "face shone with exceeding luster, even as Moses' did while in the mount of Sinai, while speaking with the Lord" (Mosiah 13:5).
e. The ancient festival appears to have been a three-day event (see Exodus 19:11), which may explain why Abinadi's trial was postponed for "three days" (Mosiah 17:6).
No other day on the ancient Israelite calendar fits the message, words, and experience of the prophet Abinadi more precisely than does the ancient Israelite festival of Pentecost. [Gordon C. Thomasson, John W. Welch and Robert F. Smith, "Abinadi and Pentecost," in Reexploring the Book of Mormon, pp. 135-138]