The Prophet ﷺ delivered a sermon during the Farewell Pilgrimage and said, "Time has come full circle to the way it was on the day Allah created the heavens and the earth. The year is twelve months, four of which are sacred. Three are consecutive, Dhul-Qadah, Dhul-Hijjah, and Muharram, and the fourth is Rajab, which falls between Jumada and Shaban."
خطب النبي ﷺ في حجة الوداع فقال: إن الزمان قد استدار كهيئة يوم خلق الله السماوات والأرض، وإن السنة احدثنا عشر شهرا، منها أربعة حرم، وثلاثة ولاء: ذو القعدة، وذو الحجة، والمحرم. والآخر رجب والآخر رجب بين جمادي و شعبان.
Tahawi reported it in Sharh Mushkil Athar (1454) from Ubayd bin Rijal, who said, Ahmad bin Salih narrated to us, who said, Ismail bin Abu Uways narrated to us, who said, Thawr bin Zayd informed me, from Ikrima, from Ibn Abbas, and he mentioned it.Its chain is hasan, on account of the discussion regarding Ismail bin Abu Uways, whom Nasai declared daif, while others accepted him as reliable. He is hasan al-hadith unless he contradicts others, since when he narrates from his memory he makes mistakes, but he has supporting evidence here.