Ezekiel, chapters one through eight, provides scriptural proof of a thirteenth month. This passage gives several specific dates. In these chapters, Yahuwah told Ezekiel to act out a parable, revealing the fate of Jerusalem for rebelling against Heaven. In Ezekiel 1:1-2, Ezekiel received a vision on the fifth day of the fourth month in the fifth year of King Jehoiahin's captivity. A few chapters later, in Ezekiel 3:15, the date of the 11th day of the fourth month in the same year is given.
In Ezekiel 4:1-11, Yahuwah tells Ezekiel to lay on his left side for 390 days and then on his right side for 40 days. This is a total of 430 days. The following passages describe Ezekiel's obedience to this instruction. The next specific date is given in Ezekiel 8:1: "And it came to pass in the sixth year [of King Jehoiachin's captivity], in the sixth month, in the fifth day of the month, as I sat in mine house . . . that the hand of . . . [Yahuwah Elohim] fell there upon me."
Ezekiel had accomplished the 430 days of lying on his side. This is why, a year and two months later, he is sitting at home. A full 430 days can only be accomplished on a lunar solar calendar during an embolismic year when an extra thirteenth month has been intercalated in. If it were a strictly solar year of 365 days, there would not have been enough time for Ezekiel to finish lying on his side and be back home by the sixth month.
Example of an original calendar with all months having 30 days
Month 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6
Days 18 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 30 + 5 = 413
Example of a 12 month Lunar calendar [plus or minus 1 or 2 days]
Month 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6
Days 18 + 30 + 29 + 30 + 29 + 30 + 29 + 30 + 29 + 30 + 29 + 30 + 29 + 30 + 5 = 407
Example of a modern Gregorian [leap year] calendar [plus or minus 1 or 2 days]
Month 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6
Days 18 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + 31 + 31 + 29 + 31 + 30 + 31 + 5 = 420
All of the above examples fall short of the 430 days required for Ezekiel’s tasks.
The full amount of 430 days could be accomplished, and still get Ezekiel back home by the fifth day of the sixth month, only if Ezekiel were using a lunar-solar calendar during an embolismic year, which had a thirteenth month as shown in the example below.
Month 4 5 6 7 8 9 10 11 12 [13] 1 2 3 4 5 6
Days 18 + 30 + 29 + 30 + 29 + 30 + 29 + 30 + 29 + [29] + 30 + 29 + 30 + 29 + 30 + 5 = 436 days
Using this calendar, Ezekiel completed his assignment and had days to spare!