34. This means that ever since Allah created the sun, the moon and the earth, the new moon takes place only once in a month; thus the year has always been of twelve months.
This has been mentioned to refute the practice of nasi (Ayat 37) whereby the pagan Arabs increased the number of the months of a year to 13 or 14 to enable them to interpose in the calendar the forbidden month which had been made lawful by them.