English Translation of Hadith
Hazrat Abu Bakr (May Allah be pleased with him) reported: The Messenger of Allah [SAWW](PBUH) said, "Time has completed its cycle and has come to the state of the day when Allah created the heavens and the earth. The year consists of twelve months of which four are inviolable; three of them consecutive – Dhul-Qa`dah, Dhul-Hijjah and Muharram and Rajab, the month of Mudar (tribe), which comes between Jumada and Shaban. What month is this?” We said, "Allah and His Messenger [SAWW](PBUH) know better". The Prophet [SAWW](PBUH) remained silent for some time until we thought that he would give it a name other than its real name. Then asked, "Is it not (the month of) Dhul-Hijjah?”. We replied in the affirmative.
[Al-Bukhari Volume 7, Book 68, Hadith Number 458]
Lesson : as mentioned above in Surah Ar-Rum [The Romans] Ayat 08 “Allah has created not the heavens and the earth, and all that is between them” The cycle of years and months (that is to say a month consists of 30 or 29 days and a year has 12 months) was completed at the time of creation of heavens and earth.