The completion of the months [was mentioned] at the beginning of the book, and we have explained them. The fasting of the Month of Ramadan is the silence of 'Abd Allah therein—up to his saying (may Allah brighten his face) regarding the saying of Allah, Blessed and Exalted be He: {The month of Ramadan [is that] in which was revealed the Quran, a guidance for the people} 1 . Then he said: "Thus, the Month is 'Abd Allah, and the Quran is Muhammad." And for this, there is a second explanation: {Ya, Seen. By the wise Quran} 2 , and he is: Muhammad. And the meaning of {in which was revealed} is: his manifestation and the revealing that he manifested from 'Abd Allah; and that is the Day of al-Fitr.
So our Master—may Allah brighten his face—clarified that the beginning of the year is the Month of Ramadan, and its end is the Month of Sha‘ban, exactly as he ordered them, may Allah sanctify his soul.